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Difference between State and props in ReactJs

In this article, we will discuss the states and props in ReactJS. Props and state both provide the details about the item but have differences. Let’s take a look at how to pass props into the component and how to update a component’s state.What is State?The status of a react class component instance can be described as an object of a collection of observed features that control the component’s behavior. In other words, the component’s state is an entity with some details that can alter during the component’s lifetime.This data is kept inside a component. This particular aspect is local or owned. The component itself uses the setStatus function to update the state. The state is an updated structure that is used to contain and can modify data or information about the component over time. The state change may occur as a user activity or device event response. It decides the actions of the component and how it is to be done by the core of the React component. As easily as possible, a state should be held. It is the local state or details of the part. Only in the component or by the component directly can it be accessed or changed. Components of react have a built-in state object. The state object is where the property values belonging to the item are stored. The component is restored when the state object changes.What are Props?React is a library focused on components that separate the user interface into reusable little bits. These components have to transmit (send data to each other) in some cases, and the way to transmit data among components is through props. “Props” is a special React keyword for proprietary purposes, used for data transmission from component to component. But the key part of this is the transmission of data with props in a uniform flow. (parent-to-child route)In addition, props data are read-only, meaning that parent data cannot be modified by child elements.Difference between State and PropsReact is an opensource JavaScript library that offers a visual overview of the JavaScript architecture for conventional MVC. React promises programmers a model in which substrates cannot directly influence enclosing components—data are downstream, data changes in HTML are efficiently modified, and the DOM is abstracted to boost performance using Virtual DOM.How can we access data from the previous component if the data is just being flowed from components to components? The answer is props. React uses data transmission props that we need to transfer to various components. The difference comes in which component the data are owned. State is owned locally and the component itself updates it. Props are owned and read-only by a parent. Props can be changed only if an upstream shift is caused by a callback function passed on to the child.A prop can be passed on to the child in the state of a parent. They apply to the same value but can only be updated by the parent variable.How are props passed into the component?We can pass props to any component by declaring HTML tag attributes.<DemoComponent sampleProp = "HelloProp" />We transfer a sampleProp in the above code snippet to the DemoComponent part. This prop has the ‘HelloProp’ value. See how we can access this advice now.In the class components to which the props are transferred, we can access any props.this.props.propName;We can use the above syntax to access any prop from within a component class. The “this.props” is a type of total object that stores all props from an item. The propname, which is the propName, is the key.Passing information from one component to other:This is one of React’s coolest characteristics. We should make it possible for components to communicate. To understand this, we will look at two components Parent and Child. We will pass information to the Child component as advice from our parent component. We can offer a part as much advice as we want. The content of a prop is not permitted to be changed. No matter what kind of component it is, nobody is allowed to change their advice, whether functional or class-based. The difference comes in which component the data are owned. State is owned locally and the component itself updates it. Props are owned and read-only by a parent. Props can be changed only if an upstream shift is caused by a callback function passed on to the child. A prop can be passed on to the child in the state of a parent. They apply to the same value but can only be updated by the parent variable.How do you update a component’s state?Although a react component can have an initial state, the actual power is in updating the state — the component should not be in either state if we don’t have to update the state. State is reserved only for data that changes our part and can be seen in the user interface.We use this.setState() instead of changing the state directly using this.state (). This is a feature for all components that use state, and allows us to inform React that the state of the component has changed. This way the component knows that it can return because its status has changed and the user interface will probably change as well. It is very efficient to use a setter function like that. React intentionally waits until all components in their event handlers call setState() before they start returning. This increases efficiency by preventing excessive re-renders. You may also ask why React does not update this, however. Two major reasons exist: The consistency of props and the state is broken, which causes problems that are very difficult to debug. This will make it difficult to introduce such new features. React will load several setState() calls for performance into a single update. Due to the asynchronous of this.props and this.state, you cannot depend on their values for the next state to be calculated. To fix it, use a second setState() form, which accepts a function instead of an object. This function is the first argument for the previous state, and the props are the second argument when the update is applied: this.setState(function(state, props) {   return {     counter: state.counter + props.increment   }; });Is state changeable?A state change takes place on the basis of the user input, which triggers an occurrence. React (with status) components are often made on the basis of state data. The initial knowledge is held by the State.Thus when the state changes, React will be notified and the DOM will be re-rendered immediately; not the whole DOM but only the modified portion. This is one of the reasons for the fast reaction.And how do you notify React? You thought: with setState ( ). The setState() method triggers the mechanism for rendering the modified components. React is notified, knows which part(s) to alter, and does so quickly without restoring the entire DOM.Is state created in the component?Let’s see the constructor method:constructor() {   super();   this.state = {     count: 0,   }; }This is where the state gets the initial data. The initial data (as above) can be hard-coded, but it can also come from props.However, it makes sense – you cannot adjust props but the data a component receives wants to do so. This is where the state enters.Component typesStateless component — Just props, no state.  Besides the render() function, there’s not much going on and all its logic is about the props that they get. This makes it easy to track them (and test for that matter).  The stately component — state as well as props. These are also called state managers. They are responsible for communication between clients and their servers (XHR, Web sockets, etc.), data processing, and user events.What happens when state changes?React Components allow you to break the UI into separate, reusable components so that you can look into every single item on an isolated basis.Components are conceptually like functions in JavaScript. They accept arbitrary inputs and return elements of react that describe what should be shown on the screen. If you have to allow the user to enter something or to alter the variables that the component is supported by, you would have to setState.State allows React components in response to user behavior, network responses, and everything else to adjust their performance over time, without violating this rule. Class-defined components provide additional functionality. Local status is the only class component function available.Can I use state in every component?In the early days, only class components, and not functional components, were included.That’s why stateless components are known for their functional components. However, state can now be used in both class and functional components following the implementation of React Hooks.You can only use status in class components if your project does not use React Hooks.The component State and Props share some common similaritiesProps and states both provide details about the item, but they are used differently and must be kept separate.ConclusionState refers to the component’s local status which cannot be used and changed outside the component and can only be used and modified within the component. On the other hand, it provides reusable components by enabling components to obtain data in the form of props from the parent component. We may change the state of a component with setState. These notifications are also triggered by events. setState is called asynchronous and merged with every entity in the current state. We may also transfer a setState function to allow us to write status changes based on the current status values. Most of your components can be stateless when you create an app. Props transfer parent-to-child data. They are unchangeable and are thus unchanged.

Difference between State and props in ReactJs

2K
  • by Abhresh S
  • 29th Apr, 2021
  • Last updated on 04th May, 2021
  • 7 mins read
Difference between State and props in ReactJs

In this article, we will discuss the states and props in ReactJS. Props and state both provide the details about the item but have differences. Let’s take a look at how to pass props into the component and how to update a component’s state.

What is State?

The status of a react class component instance can be described as an object of a collection of observed features that control the component’s behavior. In other words, the component’s state is an entity with some details that can alter during the component’s lifetime.

This data is kept inside a component. This particular aspect is local or owned. The component itself uses the setStatus function to update the state. 

The state is an updated structure that is used to contain and can modify data or information about the component over time. The state change may occur as a user activity or device event response. It decides the actions of the component and how it is to be done by the core of the React component. 

As easily as possible, a state should be held. It is the local state or details of the part. Only in the component or by the component directly can it be accessed or changed. 

Components of react have a built-in state object. The state object is where the property values belonging to the item are stored. The component is restored when the state object changes.

What are Props?

React is a library focused on components that separate the user interface into reusable little bits. These components have to transmit (send data to each other) in some cases, and the way to transmit data among components is through props. 

“Props” is a special React keyword for proprietary purposes, used for data transmission from component to component. 

But the key part of this is the transmission of data with props in a uniform flow. (parent-to-child route)

In addition, props data are read-only, meaning that parent data cannot be modified by child elements.

Difference between State and Props

React is an opensource JavaScript library that offers a visual overview of the JavaScript architecture for conventional MVC. React promises programmers a model in which substrates cannot directly influence enclosing components—data are downstream, data changes in HTML are efficiently modified, and the DOM is abstracted to boost performance using Virtual DOM.

How can we access data from the previous component if the data is just being flowed from components to components? The answer is props. React uses data transmission props that we need to transfer to various components. 

The difference comes in which component the data are owned. State is owned locally and the component itself updates it. Props are owned and read-only by a parent. Props can be changed only if an upstream shift is caused by a callback function passed on to the child.

A prop can be passed on to the child in the state of a parent. They apply to the same value but can only be updated by the parent variable.

How are props passed into the component?

We can pass props to any component by declaring HTML tag attributes.

<DemoComponent sampleProp = "HelloProp" />

We transfer a sampleProp in the above code snippet to the DemoComponent part. This prop has the ‘HelloProp’ value. See how we can access this advice now.

In the class components to which the props are transferred, we can access any props.

this.props.propName;

We can use the above syntax to access any prop from within a component class. The “this.props” is a type of total object that stores all props from an item. The propname, which is the propName, is the key.

Passing information from one component to other:

This is one of React’s coolest characteristics. We should make it possible for components to communicate. To understand this, we will look at two components Parent and Child. We will pass information to the Child component as advice from our parent component. We can offer a part as much advice as we want. 

The content of a prop is not permitted to be changed. No matter what kind of component it is, nobody is allowed to change their advice, whether functional or class-based. 

The difference comes in which component the data are owned. State is owned locally and the component itself updates it. Props are owned and read-only by a parent. Props can be changed only if an upstream shift is caused by a callback function passed on to the child. 

A prop can be passed on to the child in the state of a parent. They apply to the same value but can only be updated by the parent variable.

How do you update a component’s state?

Although a react component can have an initial state, the actual power is in updating the state — the component should not be in either state if we don’t have to update the state. State is reserved only for data that changes our part and can be seen in the user interface.

We use this.setState() instead of changing the state directly using this.state (). This is a feature for all components that use state, and allows us to inform React that the state of the component has changed. This way the component knows that it can return because its status has changed and the user interface will probably change as well. It is very efficient to use a setter function like that. 

React intentionally waits until all components in their event handlers call setState() before they start returning. This increases efficiency by preventing excessive re-renders. 

You may also ask why React does not update this, however. 

Two major reasons exist: 

  • The consistency of props and the state is broken, which causes problems that are very difficult to debug. 
  • This will make it difficult to introduce such new features. 
  • React will load several setState() calls for performance into a single update. 
  • Due to the asynchronous of this.props and this.state, you cannot depend on their values for the next state to be calculated. 

To fix it, use a second setState() form, which accepts a function instead of an object. This function is the first argument for the previous state, and the props are the second argument when the update is applied: 

this.setState(function(state, props) { 
  return { 
    counter: state.counter + props.increment 
  }; 
});

Is state changeable?

A state change takes place on the basis of the user input, which triggers an occurrence. React (with status) components are often made on the basis of state data. The initial knowledge is held by the State.

Thus when the state changes, React will be notified and the DOM will be re-rendered immediately; not the whole DOM but only the modified portion. This is one of the reasons for the fast reaction.

And how do you notify React? You thought: with setState ( ). The setState() method triggers the mechanism for rendering the modified components. React is notified, knows which part(s) to alter, and does so quickly without restoring the entire DOM.

Is state created in the component?

Let’s see the constructor method:

constructor() {
  super();
  this.state = {
    count: 0,
  };
}

This is where the state gets the initial data. The initial data (as above) can be hard-coded, but it can also come from props.

However, it makes sense – you cannot adjust props but the data a component receives wants to do so. This is where the state enters.

Component types

  • Stateless component — Just props, no state.  Besides the render() function, there’s not much going on and all its logic is about the props that they get. This makes it easy to track them (and test for that matter).  
  • The stately component — state as well as props. These are also called state managers. They are responsible for communication between clients and their servers (XHR, Web sockets, etc.), data processing, and user events.

What happens when state changes?

React Components allow you to break the UI into separate, reusable components so that you can look into every single item on an isolated basis.

Components are conceptually like functions in JavaScript. They accept arbitrary inputs and return elements of react that describe what should be shown on the screen. If you have to allow the user to enter something or to alter the variables that the component is supported by, you would have to setState.

State allows React components in response to user behavior, network responses, and everything else to adjust their performance over time, without violating this rule. Class-defined components provide additional functionality. Local status is the only class component function available.

Can I use state in every component?

In the early days, only class components, and not functional components, were included.

That’s why stateless components are known for their functional components. However, state can now be used in both class and functional components following the implementation of React Hooks.

You can only use status in class components if your project does not use React Hooks.

The component State and Props share some common similarities

Props and states both provide details about the item, but they are used differently and must be kept separate.

Conclusion

State refers to the component’s local status which cannot be used and changed outside the component and can only be used and modified within the component. On the other hand, it provides reusable components by enabling components to obtain data in the form of props from the parent component. 

We may change the state of a component with setState. These notifications are also triggered by events. setState is called asynchronous and merged with every entity in the current state. We may also transfer a setState function to allow us to write status changes based on the current status values. 

Most of your components can be stateless when you create an app. Props transfer parent-to-child data. They are unchangeable and are thus unchanged.

Abhresh

Abhresh S

Author

An Online Technical Trainer by profession! And Content writer by hobby! Interested in sharing quality knowledge to make the Industry grow better towards better success and better tomorrow! With a Guru Mantra of - "Keep Learning & Keep Practicing".

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So, enterprise grade web-apps and web-apps with a lot of traffic prefer Java, because it handles loads better. The most popular frameworks for backend development in Java are Spring Framework and Hibernate. Some good beginner's tutorials are - JavaScript It is a very popular choice for backend development, because on the frontend side JavaScript is the only choice. So, a lot of frontend engineers can take this choice to become Full-stack developers. Node.js It allows developers to use JavaScript to write server-side code, through which they can write APIs. Actually, the API part can be done by numerous frameworks of Node.js out of which Express is widely used. The other popular framework is Fastify. Some good beginner's tutorials are - Python Python is one of the most popular languages among developers and has been used in a variety of fields. The two most popular frameworks for Python are Flask and Django. Some good beginner tutorials are - C# It is a very popular programming language which was developed by Microsoft and it has the power of C++. Its popularity increased once the .NET framework was released for backend development. As Microsoft is very popular in enterprises, the .NET framework is generally preferred in enterprises. A good tutorial to learn .NET is - Go Go language which is also referred to as Golang, has gained popularity in recent years. It is used a lot in Backend programming and the two popular frameworks are Gin and Beego. DatabaseFor a Backend engineer, after making APIs with framework based on language, it's time to learn about Databases. Databases are used to store most of the things which we see in a web-app, from user login credentials to user posts and everything else. In the earlier days we only used to have one type of Database and that was Relational databases, which use tables to store data. Now we have two other categories also, one being NoSQL databases and the other In-memory databases. 1. Relational databases Relational databases allow you to create, update and delete data stored in a table format. This type of database mostly uses SQL language to access the data, hence is also known as an SQL database. MySQL It is one of the oldest databases and was released in 1995. It is an open-source database and was very popular in the 2000s with the rise of LAMP (Linux, Apache, MySQL, PHP) stack. It is still widely in use, but there are other popular Relational databases. A good tutorial to learn MySQL is - PostgreSQL PostgreSQL, which is also known as Postgres is also an old open-source Relational database, which was released in 1996. But it gained popularity recently, as it goes very well with modern stacks containing NodeJS and other backend technologies. A good tutorial to learn PostgreSQL is - Oracle is the most popular and oldest relational database. It was released in 1979 and still remains the number one preference for enterprise customers. All the big banks and other organizations, run on Oracle databases. So, the knowledge of Oracle is a must in many companies for an Engineer. A good tutorial to learn Oracle is - MS-SQL MS-SQL is also known as Microsoft SQL and is yet another commercial Relational database. It has got different editions, used by different audiences. It is also heavily used by enterprise users and powers a whole lot of big systems around the world. A good tutorial to learn MS-SQL is - 2. NoSQL databases NoSQL databases are also called non-SQL databases. The NoSQL databases mainly store data as key-value pairs, but some of them also use a SQL-like structure. These databases have become hugely popular in the 21st century, with the rise of large web-apps which have a lot of concurrent users. These databases can take huge loads, even millions of data connections, required by web-apps like Facebook, Amazon and others. Beside this, it is very easy to horizontally scale  a NoSQL database by adding more clusters, which is a problem in Relational Databases. MongoDB It is the most popular NoSQL database, used by almost every modern app. It is a free to use database, but the hosting is charged if we host on popular cloud services like MongoDB atlas. Its knowledge is a must for backend engineers, who work on the modern stack. MongoDB uses json like documents to store data. A good tutorial to learn MongoDB is - It is a proprietary database service provided by Amazon. It is quite similar to MongoDB and uses key-value pairs to store data. It is also a part of the popular AWS services. A good tutorial to learn DynamoDB is-Cassandra is an open-source and free to use NoSQL database . It takes a different approach when compared to other NoSQL databases, because we use commands like SQL, which are known as CQL (Cassandra Query Language). A good tutorial to learn Cassandra is - 3. In-memory databases The in-memory database is a database, which keeps all of the data in the RAM. This means it is the fastest among all databases.  The most popular and widely used in-memory database is Redis. Redis Redis (Remote Dictionary Server) is an in-memory database, which stores data in RAM in a json like key-value format. It keeps the data persistent by updating everything in the transaction log, because when systems are shut down their RAM is wiped clean. A good tutorial to learn Redis is - StorageStoring the data is an important part of any application. Although this is mainly DevOps territory, every backend developer should know the basics for the same. We need to store the database data and also the backend code. Beside this the frontend code must also be stored somewhere. Nowadays everything is stored in the cloud, which is preferred by individuals, startups and enterprises. The two most popular cloud-based storages are – Amazon S3 Azure Blob Storage Good beginner's tutorials for both areServices and APIsThese are theoretical concepts and are implemented by various services, but a backend engineer should know them and how to use them. Restful APIs This is by far the most popular way to get data from a database. It was made more popular, with the rise of web-apps. We do GET, PUT, POST and DELETE operations to read, update, create or delete data from databases. We have earlier discussed different languages and frameworks, which have their own implementations for these operations. Microservices Architecture In microservice architecture, we divide a large and complex project into small, independent services. Each of these is responsible for a specific task and communicates with other services through simple APIs. Each service is built by a small team from the beginning, and separated by boundaries which make it easier to scale up the development effort if needed. GraphQL It is the hottest new kid in the block, which is an alternative to the Restful APIs. The problem with Restful APIs is that if you want some data stored in database, you need to get the whole data sent by the endpoint. On the other hand, with GraphQL, you get a query type language which can return only the part of the data which you require.  DevOps & DeploymentA backend engineer requires a fair bit of DevOps knowledge. So, we will next deep dive into the methodologies in DevOps. 1. Containerization & Orchestration Containers are a method of building, packaging and deploying software. They are similar to but not the same thing as virtual machines (VMs). One of the primary differences is that containers are isolated or abstracted away from the underlying operating system and infrastructure that they run on. In the simplest terms, a container includes both an application’s code and everything that code needs to run properly. Container orchestration is the automatic process of managing the work of individual containers for applications based on microservice architecture. The popular Containerization and Orchestration tools are – Kubernetes Docker Good beginner's tutorials for both are -2. DevOps DevOps is a set of practices that combine software development (Dev) and IT operations (Ops). It aims to shorten the systems development life cycle and provide continuous delivery with high software quality. The two most popular DevOps services are AWS and Azure. Both of them are cloud based and are market leaders. Both of these platforms contain a wide variety of similar services. AWS It consists of over 200 products and services for storage, database, analytics, deployment, serverless function and many more. AWS is the market leader as of now with 33% of market share. The AWS certifications are also one of the most in-demand certifications and a must for frontend engineers as well as Backend engineers. Azure Microsoft Azure is second in terms of market share of cloud-based platforms, with 18% of the market. It also consists of SaaS (Software as a Service), PaaS (Platform as a Service) and IaaS (Infrastructure as a Service) like AWS. 3. PaaS (Platform as a Service) There are several smaller players, which provide Platform as a Service and are much easier to use than services like AWS and Azure. With these services you can directly deploy your React or other web-apps, by just hosting them on GitHub and pushing the code. These services are preferred a lot by freelancers, hobbyists and small companies as they don’t require investment in learning complicated services like AWS and Azure. The three most popular PaaS services are Digital Ocean Heroku Netlify 4. Serverless Serverless computing is an execution model where the cloud provider (AWS, Azure, or Google Cloud) is responsible for executing a piece of code by dynamically allocating resources and only charging for the number of resources used to run the code. The code is typically run inside stateless containers that can be triggered by a variety of events including http requests, database events, queuing services, monitoring alerts, file uploads, scheduled events (cron jobs), etc. The code that is sent to the cloud provider for execution is usually in the form of a function. AWS Lambda It is an event-driven, serverless platform which is part of AWS. The various languages supported by AWS Lambda are Node.js, Python, Java, Go, Ruby and .NET. AWS Lambda was designed for use cases such as updates to DynamoDB tables, responding to a website click etc. After that it will “spin down” the database service, to save resources. Azure Functions They are quite similar to AWS Lambda, but are for Microsoft Azure. Azure functions have a browser-based interface to write code to respond to events generated by http requests etc. The service accepts programming languages like C#, F#, Node.js, Python, PHP and Java. Serverless Framework It is an open-source web-framework written using Node.js. The popular services like AWS Lambda, Azure functions and Google cloud functions are based on it. CI/CD A backend developer should know the popular CI/CD (Continuous Integration/Continuous deployment) tools. These tools help to automate the whole process of building, testing and deployment of applications. Github Actions  It is a freely available CI/CD pipeline, which directly integrates to your GitHub based project and can be used in variety of languages. Jenkins Jenkins is the most popular CI/CD automation tool, which helps in building, testing and deployment of applications. Jenkins was written in Java and over the years has been built to support over 1400 plugins, which extend its functionalities. Circle CI Circle CI is also a CI/CD automation tool, which is cloud based and so it is different from Jenkins. It is much easier to use than Jenkins, but has a smaller community and lower user base. SecuritySecurity is an important aspect of any application. Most applications containing user personal data, like email etc, are often targeted by hackers. OWASP The Open Web Application Security Project (or OWASP), is a non-profit organization dedicated to web application security. They have free material available on their website, making it possible for anyone to improve their web application security. Protecting Services & databases against threats Hackers target databases of popular web-apps on a regular basis to get sensitive information about their customers. This data is then sold to the highest bidder on the dark-net. When such public breaches are reported, then it's a reputation loss for the enterprise also. So, a lot of emphasis should be given to Authentication, Access, Backups, and Encryption while setting up a database. The databases should also be monitored for any suspicious activities. Besides this the API routes also need to be protected, so that the hacker cannot manipulate them. Career roles Most of the companies hire Frontend developers, Backend developers and DevOps engineers separately. This is because most of the enterprise projects are huge, in which roles and responsibilities are distributed. But there is a huge demand for Full Stack developers in the startup sector in US and India. These companies need specialists who can get the product out as soon as possible with agile and small teams. Top companies hiringAlmost every company on the planet is hiring web-developers or outsourcing the development work. Since the past decade, the demand for developers has risen exponentially. The top technology companies which hire full stack developers are Facebook, Amazon, Apple, Netflix, Google, Uber, Flipkart, Microsoft and more.  The sites of each of these companies are web-apps (excluding Apple and Microsoft), with complex frontend and backend systems. The frontend generally consists of React or Angular and the backend is a combination of various technologies. The DevOps part is also quite important in these web-apps as they handle millions of concurrent connections at once.Salaries  The salary of a beginner Frontend developer in India starts from Rs. 300,000($ 3980) per year in service-based companies to Rs. 12,00,000($ 15,971) per year in the top tech companies mentioned above. The salary of a Beginner Full-Stack developer in India starts at Rs. 4,50,000 ($ 5989) per year in service companies to Rs. 12,00,000($ 15,971) per year in top tech companies. The salary for an entry level Frontend developer in USA is $ 59,213 per year and for an entry level Full stack developer is $ 61,042 per year.Below are some sources for salaries. Top regions where there is demand There are plenty of remote and freelancing opportunities in web-development across the world. The two countries with most developers and top tech companies are USA and India. Silicon Valley, which is the San Francisco Bay Area, in Northern California, USA is the hub of technology companies.  The top city in India to start a developer job is the Silicon Valley of India – Bengaluru. The number of jobs is more than all the other cities combined and it also has a very good startup ecosystem. Almost all the big technology companies mentioned earlier and top Indian service companies are located in the city. After Bengaluru, the city where the greatest number of technology jobs are based is Hyderabad, followed by Chennai and then Pune. Entry PointsThe demand for web-developers is high and anyone with a passion for creating apps can become a web-developer. An Engineering degree is not mandatory to land a job as a web developer.  The most in-demand skill today and for the next 5 years is React and its ecosystem. So, if you know HTML, CSS, JavaScript and React, it is impossible to not get a job. Career Pathway  Most people start as an intern Front-end developer or Intern Full-Stack developer and in many cases Intern Backend developer. Many companies directly hire junior Frontend/Backend/Full-stack developers.  After that, the next step is the role of Senior Frontend/Backend/Full-stack developers. Many Frontend and Backend developers become full stack developers at this level, by learning additional technologies. Senior resources in Frontend/Backend/Full-stack can then go on to assume Team Lead roles. These people manage small teams in addition to being individual contributors.  After this a professional can become a Project manager, whose main responsibility is managing the team. Another role is that of Technical Project Manager, who manages the team and also has hands-on knowledge in Technology. The last role at this level is that of a Software Architect, who handles and designs big projects and has to look at every aspect of the technology to create the enterprise app. Generally Full-stack developers are preferred in this role, as they need to know all technologies. The highest career milestone is CTO or Chief Technology Officer, who handles all the technology teams and makes all technology decisions in a Technology company. Job SpecializationThere are some Full stack development specializations which I see nowadays in the industry. Full stack developers who work with React in the Frontend and Java in the Backend are in great demand. Similarly, developers who work with Angular in the Frontend and .NET in the backend are in great demand.How KnowledgeHut can helpjourney. Beside these there are many other free resources on the internet, but they are not organized and don’t have a structured approach.   This is where KnowledgeHut shines and serves as a one stop shop alternative with its comprehensive Instructor-led live classes. The courses are taken by Industry experts and are perfect for aspirants who wish to become Frontend or FullStack developers.  Links for some of the popular courses by KnowledgeHut are appended below-CSS3JavaScriptReactJSNodeJSDevopsConclusion This completes our article on the Full stack developer journey by combining both the Frontend and backend roadmap. There are many people who become backend developers first by working on languages like Java and then go on to learn React to become full stack developers.  Again, many developers learn front-end development first with frameworks like React, and then become full stack developers by learning Node.JS. This path is easier for developers because both React and Node.JS use the same language which is JavaScript.  We hope you have found this blog useful, and can now take the right path to become a full stack developer. Good luck on your learning journey!
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The 2021 Learning Path To Becoming a Full Stack We...

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Back Up, Restore, and Migrate a MongoDB Database

Popular among both enterprises and startups, MongoDB is a database that is perfectly suited for web-apps that need to scale once the user base increases. MongoDB is different from traditional relational databases because it uses json like objects to store data, instead of tables in relational databases. In this post, we will learn to backup and restore a MongoDB database. In all software products there is an import and export feature, which in database terms, deals with human-readable format. On the other hand, the backup and restore operations use MongoDB specific data, which preserve the MongoDB attributes.  So, when migrating the database, we should prefer backup and restore over import and export. But we should also keep in mind that our source and target systems are compatible, which means that both should be Windows or both should be a Linux based system like Ubuntu/Mac. Prerequisites We are using Windows 10 in this tutorial. Please make sure you have downloaded the MongoDB Community Server and installed in it. It is a very easy setup and you will find lot of good articles on the internet detailing this out. Please ensure that you have added it in the Environment variable in your PC. Backup Considerations In a production environment, backups act as a snapshot of the database at a certain point. Large and complex databases do fail or can be hacked. If that happens, we can use the last backup file to restore the database to the point, before it failed. These are some of the factors which should be taken into consideration when doing a recovery.  1. Recovery Point Objective We should know the objective of the recovery point, which means how much data we are willing to lose during a backup and restoration. A continuous backup is preferred for critical data like bank information and backups should be taken several times during the day. On the other hand, if the data doesn’t change frequently, then the backup can be taken every 6 months.  2. Recovery Time ObjectiveThis tells how quickly the restoration can be done. During restoration the application will be down for some time; and this downtime should be minimized, or else customer relationships will be lost.  3. Database and Snapshot IsolationThis refers to the distance between the primary database server and the backup server. If they are close enough i.e., in the same building, then the recovery time reduces. However, in the event of a physical event such as a fire, there is a likelihood of it been destroyed with the primary database.   4. Restoration Process We should always test our backups in test servers to see if they will work, in case a restoration is required.  5. Available Storage Backup of database generally takes a lot of space and in most cases, it will never be required. So, we should try to minimize the space taken on the disk, by archiving the database into a zip file.  6. Complexity of DeploymentThe backup strategy should be easy to set and should be automated, so that we don’t have to remember to take the backup after regular intervals. Understanding the Basics The first thing that we should know is that MongoDB uses json and bson(binary json) formats for storing data. So, people coming from a JavaScript background can relate to objects for json, which have a key-value pair. Also, json is the preferred format in which we receive or send data to an API endpoint. You can check the json data of a MongoDB database in any tool or online editors. Even the famous Windows application Notepad++ has a json viewer. An example of a json document looks like below. As we can see from the above example, json is very convenient to work with, especially for developers.  But it doesn’t support all the data types available in bson. So, for backup and restoring, we should use binary bson. The second thing to keep in mind is that MongoDB automatically creates databases and collection names if they don’t exist during restore operations. Third, since MongoDB is a document-based database, in many user cases we store large amounts of data in one collection, such as the whole post of an article. MongoDB is also used extensively in large databases and big data. So, reading and inserting the data can consume a lot of CPU, memory and disk space. We should always run the backups during the non-peak hours like night. As already mentioned earlier, we can use import and export functions for backup and restoration of MongoDB databases, but we should use commands like mongodump and mongorestore to backup and restore respectively. MongoDB backup We will first cover backing up the MongoDB database. For this we use the mongodump command.  First open the Windows command prompt and go to the location in which MongoDB is installed. If you have chosen the default setting, while installing MongoDB though the pop-up it will be installed in a location like C:\Program Files\MongoDB\Server\4.4\bin The version number only will change if you are reading this blog in the future. Also, note that it’s better to run the command prompt in the Admin mode. So, once we open the command prompt, we need to change the directory to MongoDB bin folder by giving the below command. cd C:\Program Files\MongoDB\Server\4.4\binNow, enter mongod and press enter. It will show some json text.Now, we can backup to any location. For this post I am backing up on my Desktop in a Backup folder, which I have created through the command line.Now, we have to run mongodump command, but it should be also present in our MongoDB bin folder. If it is not present, we need to download it from and install it. After this, copy the entire exe files from the download to the MongoDB bin folder. MongoDB Backup with no option Now, run the mongodump command from the bin directory. Here, we are not giving any argument so the backup of the whole database will be taken in the same bin directory.MongoDB Backup to an output directory Now, run the mongodump command from the bin directory. Here, the argument –out specifies the directory in which the data backup will be maintained. In our case we are giving the Backup folder in the  Desktop, which we have created earlier. mongodump --out C:\Users\pc\Desktop\Backup Now, go to the desktop and you can find the backup that has been created in our Backup folder.  MongoDB Backup a specific database Now, we can also backup only a database in mongodump using the –db option. I have an example database, so to backup only that I will use the below command. mongodump --db example --out C:\Users\pc\Desktop\Backup As, you can see in the below output only the example database was backed up. MongoDB Backup a specific collection Now, if we want to only backup a specific collection, we need to use the –collection option and give the collection name. Also, note that the database name is mandatory in this case, as mongodb needs to know about the database to search for the collection. I have a products collection within the example database, so to backup only that I will use the below command. mongodump --db example --out C:\Users\pc\Desktop\Backup –collection products As, you can see in the below output only the products collection from example database was backed up. MongoDB Backup from remote MongoDB instances We can get the backup from remote mongodb instances also. I have a lot of MongoDB databases for my personal projects on MongoDB atlas, which is the free to use Cloud database for MongoDB. To get a backup of remote databases, we have to use the connection string with –uri parameter. I used the below command. mongodump --uri "mongodb+srv://xxxx:xxxxxxxxxxx@cluster0.suvl2.mongodb.net/xxxxxDB?retryWrites=true&w=majority" --out C:\Users\pc\Desktop\Backup You can see in the below output the backup of the remote instance. MongoDB Backup procedures We should try to make the backup procedure as automated as possible. One of the best ways is to use a cron job, so that it can run every day. As, discussed earlier it is best to run the backup in the night when the database has the least load.  Setting up a cron job is easier on a Linux or a Mac because the Windows equivalent of it is not good. Alternatively, you can do install mongodb in WSL2 for Windows which supports Ubuntu.  Suppose, on a Linux host which has a mongoDB instance running, you want to run the backup at 04:04 am daily. For this in the terminal, open the cron editor by running the below command in the terminal. sudo crontab –e Now, in the cron editor, you need to add a command like below for our case. 4 4 * * * mongodump --out /var/backups/mongobackups/`date +"%m-%d-%y"`Restoring and migrating a MongoDB database When we restore the MongoDB database from a backup, we will be able to take the exact copy of the MongoDB information, including the indexes. We restore MongoDB by using the command mongorestore, which works only with the binary backup produced by mongodump. Now, we have taken the backup of example database earlier and it is in our Backup folder. We will use the below command to restore it. In the arguments we will specify the name of the database first with –db option. After that with –drop, we make sure that the example database is first dropped. And in the final argument, we specify the path of our backup. mongorestore --db example --drop C:\Users\pc\Desktop\Backup\example Now, if we check in terminal, we have our example database restored properly. Conclusion In this article, we have learned about MongoDB backup and restore. We have learned the different options for the backups, and why and when backups are required. Keep learning! 
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Back Up, Restore, and Migrate a MongoDB Database

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How to Work With Forms In JavaScript

Forms also referred as web forms are a very important part of front end web application development for sake of interaction with users. Most commonly, forms are used to collect the data from users or provide a provision for user to control the user interface. Forms are great potential assets if correctly used in building an interactive web application. We would be touch basing some of the essential aspects of them like HTML structure, styling form controls, events, data validation and submitting data to server.Understanding forms in detail needs expertise in other areas than just HTML like styling form controls (CSS), scripting to validate or create custom controls (JavaScript).We would be referring or using libraries like Jquery (for document traversal, manipulation etc) and parsley (form validation library) to build better forms.A typical form’s HTML is made of HTML elements called as form controls like single or multiline text fields, dropdowns, checkboxes, button etc mostly created using element with specific type being set on Type attribute. These form controls can be programmed to add some validations to support specific values based on constraints set on them. These controls can be enriched to support accessibility for enabling the interaction for less privileged users.Let’s create a simple html page to build a form.           Learning Forms       All forms have to start with element which is container having the form fields user would interact with. All attributes of element are optional but for programming forms to capture data we need at least ‘action’ and ‘method’ attributes.action – is basically the URL where the form fields data would be sent to.method – corresponds to the HTTP method to submit the form data. Possible HTTP method names which can be set as values are post and get. And another value dialog is set when form is imbedded inside a .Note: Both formaction and formmethod can be overridden by button, input with type submit elements which we will learn as we go forward.Refer to this link to know more about form attributes.Let’s add a form element to our body with action (“”) and method(“get”). This implies that form will send a GET request to the current URL. If it is post then it would be a POST request to the URL in action. Add few fields to form say name, email and a submit button using with type being specified as text, email and submit respectively.Note: The tag is an empty element, meaning that it doesn't need a closing tag. Value attribute can be populated to set the default value.          Enter your name:                    Enter your email:                       Save and open the html in chrome or your preferred browser. Clicking on ‘Click me!’ should send a http get call with empty name and email.Note: We can use instead of with type as submit. The difference is that button can contain HTML content allowing to create a complex button whereas input allows only plain text.Let’s understand the Sending of form data.If we observer all the form fields again, we have added an attribute called ‘name’. This property is important to inform that which data is associated with which form field i.e. name/value pairs. Try adding some data to our fields rendering in html (say myName and first.last@email.com) and click submit button. You should see the data being sent as query parameters in the browser URL.?name=myName&email=first.last@email.com.Change the Form method value to POST instead of GET and send the submitted data by clicking the ‘Click me!’ button. You should be seeing Form Data being sent but the browser URL will not get update.name: myName email: first.last@email.comAll this while, we have our action method being set as empty. Replace this with another URL on server side say ‘/captureFormData’. Now on clicking submit button the data should be received by the script at ‘/captureFormData’ with key/value items contained in the HTTP request object.Note that each server-side language like Node.js, C# etc have their own way of handling the submitted form data. And this blog would not cover those topics and it is beyond the scope.Let’s refine our basic form structure with help of other HTML elements like , , etc. Though we used few of them in basic example. Let’s go little deep on them.Note: Nesting of form inside another form is unacceptable as it might result in unpredictable behavior. is a convenient way of grouping for sake of styling and semantic purpose. This control can be associated with so that some assistive technologies can read this legend and associate it with the controls inside the . Let’s understand this will an example:         Interested programming language                             JavaScript                                     CSharp                                     Java               When reading the above form by any screen readers, it will read as “Interested programming language JavaScript” for the first radio, “Interested programming language CSharp” and “Interested programming language Java” for second and third radio.Imagine if you have a long form with multiple fields. It would help to improve the usability if we can categorize/section them with the help of . It would even help to improve the accessibility of forms.Talking about accessibility, with the associated correctly with the via its for attribute (which contains the element's id attribute), a screenreader will read out something like "name, edit text" for below one.Enter your name: Another advantage of having label associated with input of type text, radio etc is they are clickable too.  If you click on a label then the associated input control will get the focus. If the input control is of type checkbox or radio, clicking on label will select the check box and radio. This will be useful as clickable area of checkbox or radio is small and having label gives provision to select it easily.Note: We can always associate multiple labels to a single input control but it is not a good idea as it will impact the accessibility and assistive technologies. along with can be used to separate the functionality in a form and group the same purpose elements like radio buttons.Here is an example of the same.               Contact information                   Title                                                                             Mr                                                                                                 Mrs                                                                               Name:                                                           E-mail:                                                           Password:                                                 Additional information                               Social type:                                 LinkedIn             Twitter             Instagram                                                 Phone number:                                                           Submit                   Every time you like to create an HTML form you need to start using element and  nesting all the content controls inside it. Most of the assistive technologies and browser plugins can help to discover elements and implement special hooks to make them easier to use.We have already some of the form elements like , , , , , and . Other common input types are button, checkbox, file, hidden, image, password, radio, reset, submit, and text.Input types.Attributes of Input.Few attributes on element help in validating the data like required, max, maxlength, min, minlength, multiple, pattern, step etc based on their respective type.Also other attributes on of type submit/image like formaction, formmethod, formnovalidate, formenctype etc helps in overriding the form level methods.ValidationBefore submitting the data to the server, it is important to perform some client side validation to avoid unwanted round trips. Client-side validation is needed but it is not a replacement to the server side validation. Advantage of having client side validation is to capture the invalid data and fix it immediately.Some of the important and popular checks which are most commonly used on client areField requiredSpecific data formatEnter valid email addressPassword and more…Let’s build a form with the above validation checks.                         Do you have experience in programming ?*                     Yes           No                             How many years of experience you have ?                                     What's your programming language?*                           TypeScript           Java           CSharp           Ruby           Go           Swift                             What's your company e-mail address?                             Cover letter                             Submit       Say, if we enter an value which is more than 40 in experience field. We should see an inbuilt error as shown below:All these validations and notifications are coming out of the box. Thanks to inbuilt functionality in control. Let’s see how we can perform validation of forms using JavaScript and take control of look and feel of error message.Most browsers support constraint validation API by providing few validation properties on HTML elements like , , , etc.validationMessage: we can customize this message if the control value failed validation otherwise it will return an empty string. It is dependent on other constraint i.e. willValidate and isValid.willValidate: If element is validated then it will be true otherwise false.validity: is the validity state of the element and it is dependent on other properties likepatternMatch for specified pattern attribute,tooLong and tooShort are for string fields based on maxLength and minLengthrangeOverflow and rangeUnderflow for numeric fields based on max and min attributestypeMatch for fields which are based on email or url.valid if all the validation constraints are metvalueMissing if the field is set as required.Along with properties, we do also have methods to perform validation like checkValidity() which returns true or false and setCustomValidity(message) is to set the message if the element is considered invalid. Also if the element is invalid then checkValidity will raise an event called invalid Event.Let’s create a simple form and customize the validation message.       Please enter an email address:             Submit     Add a script tag and customize the message as shown below:     const email = document.getElementById("mail");     email.addEventListener("input", function (event) {       if (email.validity.typeMismatch) {         email.setCustomValidity("I am expecting an e-mail address!");       } else {         email.setCustomValidity("");       }     });   Here we are listening to the input event on email field and checking if the validity on the control is valid or not and based on that we are setting the custom message.Here are we relying on inbuilt validation method. Let’s disable the validation at form level by with the help of ‘novalidate’ and take control over validation. This would mean the browser will not perform auto check on validation before sending the data. But still we have access to constraint validation API to perform validation ourself.Refine the above form to add few addition validation like required and minLength etc.               Please enter an email address:                             Submit     Let’s update the script to handle the validation     const form  = document.getElementsByTagName('form')[0];     const email = document.getElementById('mail');     const emailError = document.querySelector('#mail + span.error');     email.addEventListener('input', function (event) {       // Each time the user types something, we check if the form fields are valid.       if (email.validity.valid) {         // In case there is an error message visible, if the field is valid, we remove the error message.         emailError.textContent = ''; // Reset the content of the message         emailError.className = 'error'; // Reset the visual state of the message       } else {         // If there is still an error, show the correct error         showError();       }     });     form.addEventListener('submit', function (event) {       // if the email field is valid, we let the form submit       if(!email.validity.valid) {         // If it isn't, we display an appropriate error message         showError();         // Then we prevent the form from being sent by cancelling the event         event.preventDefault();       }     });     function showError() {       if(email.validity.valueMissing) {         // If the field is empty display the following error message.         emailError.textContent = 'You need to enter an e-mail address.';       } else if(email.validity.typeMismatch) {         // If the field doesn't contain an email address display the following error message.         emailError.textContent = 'Invalid value is entered, expected an e-mail address.';       } else if(email.validity.tooShort) {         // If the data is too short display the following error message.         emailError.textContent = `Email should be at least ${ email.minLength } characters; you entered ${ email.value.length }.`;       }       // Set the styling appropriately       emailError.className = 'error active';     } Reload the HTML and try entering an invalid email address, the corresponding error message should be displayed.Note: In the current scope of this blog, we are not working on styling.Is it possible to validate forms without built in APIs ? Let’s see with the same example.We would consider the same form again but have lot of functionality in                           Please enter an email address:                                             Submit           const form  = document.getElementsByTagName('form')[0];     const email = document.getElementById('mail');     let error = email.nextElementSibling;     const emailRegExp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$/;     function addEvent(element, event, callback) {       let previousEventCallBack = element["on"+event];       element["on"+event] = function (e) {         const output = callback(e);         // A callback that returns `false` stops the callback chain and interrupts the execution of the event callback.         if (output === false) return false;         if (typeof previousEventCallBack === 'function') {           output = previousEventCallBack(e);           if(output === false) return false;         }       }     };     // Now we can rebuild our validation constraint. Because we do not rely on CSS pseudo-class, we have to explicitly set the valid/invalid class on our email field     addEvent(window, "load", function () {       // Here, we test if the field is empty (remember, the field is not required)       // If it is not, we check if its content is a well-formed e-mail address.       const test = email.value.length === 0 || emailRegExp.test(email.value);       email.className = test ? "valid" : "invalid";     });     // This defines what happens when the user types in the fiel     addEvent(email, "input", function () {       const test = email.value.length === 0 || emailRegExp.test(email.value);       if (test) {         email.className = "valid";         error.textContent = "";         error.className = "error";       } else {         email.className = "invalid";       }     });     // This defines what happens when the user tries to submit the data     addEvent(form, "submit", function () {       const test = email.value.length === 0 || emailRegExp.test(email.value);       if (!test) {         email.className = "invalid";         error.textContent = "Expecting an e-mail";         error.className = "error active";         return false;       } else {         email.className = "valid";         error.textContent = "";         error.className = "error";       }     });   On refreshing the page, the output with invalid email address should be displayed as shown below.In real time applications, we can rely on existing libraries like Parsley along with JQuery which would ease our life by taking away lot of complexity.Overview of Parsley:Parsley is a front-end javascript validation library which helps to give proper feedback to user on submission of form. As mentioned earlier, it is not a replacement of server side validation. Parsley library helps us to define our own validation.Parsley uses a DOM API namely ‘data-parsley-’ prefix on the existing properties. For example if we want to add this on a property say ‘sample’ then we would add as [data-parsley-sample=’value’]. This will allow us to configure pretty much everything without any configuration or custom function.There is no specific installation process but adding the corresponding script tags will enable the validation. Parsley is relied on Jquery so it has to be included as well.             ...                 $('#form').parsley();     Assumption is that we have downloaded the Jquery and Parsley minified librarie and added it to our working directory. Otherwise we can refer to CDN location as shown below.   Adding attribute ‘data-parsley-validate’ to each form will allow us to validate. And “$(‘#form’).parsley()” will manually bind Parsley to your forms.Let’s understand further by configuring the attributes via JavaScript. For which, lets add two input fields inside the form element.                 Also let’s update the content to perform some pre-defined validation based on attributes.       var instance = $('#first').parsley();       console.log(instance.isValid()); // maxlength is 42, so field is valid       $('#first').attr('data-parsley-maxlength', 4);       console.log(instance.isValid()); // No longer valid, as maxlength is 4       // You can access and override options in javascript too:       instance.options.maxlength++;       console.log(instance.isValid()); // Back to being valid, as maxlength is 5       // Alternatively, the options can be specified as:       var otherInstance = $('#second').parsley({         maxlength: 10       });       console.log(otherInstance.options);     In the console.log, we should see thistrue false true {maxlength: 10}Options are inherited from the global level to form level and further to field. So if we set the options at global level then the same can be observed at field level.   Parsley.options.maxlength = 42; // maxlength of 42 is declared at global level var formInstance = $('form').parsley(); var field = $('input').parsley(); console.log(field.options.maxlength); // Shows that maxlength is 42 inherited from global Parsley.options.maxlength = 30; console.log(field.options.maxlength); // Shows that maxlength is automatically 30 formInstance.options.maxlength++; console.log(field.options.maxlength); // Shows that maxlength is automatically 31We can also add our own custom validations. Let understand this with an example.                     window.Parsley.addValidator('multipleOf', {         requirementType: 'integer',         validateNumber: function(value, requirement) {           return 0 === value % requirement;         },         messages: {           en: 'This value should be a multiple of %s',         }       });     Here we are adding a new attribute namely ‘data-parsley-multiple-of’ which takes only numeric values which are multiples of 3.In window.Parsley, we added a new validator with name ‘multiple-of’ with an object containing few important properties like ‘requirementType’, ‘validateNumber’ and ‘messages’ to be shown. This properties helps the library to check if the input value is valid or not.Similar to validateNumber, other properties are also there for different types like validateString, validateDate and validateMultiple.Also for requirementType, we have different options like string, number, date, regexp, boolean etc.Messages by default has English format, to support multiple locales we need to add the specific localization and also add specific locale.Events: Parsley triggers events that allows ParsleyUI to work and for performance reasons they don’t rely on JQuery events but the usage is similar to JQuery i.e. parsley events will also bubble up like JQuery events. For example, if a field is validated then the event ‘field:validate’ will be triggred on the field instance then on to form instance and finally to the window.Parsley.$('#some-input').parsley().on('field:success', function() {         // In here, `this` is the parlsey instance of #some-input       });       window.Parsley.on('field:error', function() {         // This global callback will be called for any field that fails validation.         console.log('Validation failed for: ', this.$element);       });Many times, we need some validation based on the response from server. Parsley provides an attributes i.e. data-parsley-remote and data-parsley-remote-validator to perform the same.Let’s consider this HTMLLet’s add the async validator on the window.Parsley object.window.Parsley.addAsyncValidator('customValidator', function (xhr) {           console.log(this.$element); // jQuery Object[ input[name="q"] ]           return 404 === xhr.status;         }, 'customURL');Parsley is a very useful and powerful JavaScript form frontend validation library.Note: For developers building react based web applications, they can rely on FORMIK which is most popular library for building forms in React and React Native.ConclusionForms are important in HTML and it was needed and still needed now. is an html tag that allow us to perform HTTP methods like GET/POST operation without writing any code in JavaScript. Form defines an boundary to identify all set of the form field elements to be submitted to the server. For example, if we perform an enter key or clicking on submit button , the agent triggers form submission data based on each form field value to the server based on the action URL on the form.Before HTML5, all the elements are expected to be part of the to send the data to server. In HTML5, they maintained the backward compatibility and also enhanced the capabilities who may want to use AJAX and don’t want to rely on default behaviours i.e. they have enabled designers who expect more flexibility in having their form elements outside the form and still maintain the connections with the form. 
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How to Work With Forms In JavaScript

Forms also referred as web forms are a very import... Read More