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Why ReactJS is taking over Frontend Development

History of JavaScript Today, we see JavaScript used pretty much everywhere. For the seventh year in a row, we see it ranking as the most popular and widely used programming language, a good 67.8% of developers having used it in 2019. JavaScript is used to build 95.2% (1.52 billion) websites today, including Facebook and YouTube and some of the most popular and useful apps such as Google Maps and eBay. Let’s take a closer look at what JavaScript is, how and why it was created, and how it seems to be taking over front-end development. It all began in the late 90s when Netscape Navigator, a popular browser was launched by Netscape Communication. In the initial days of Netscape, it was just a software which was able to render static HTMLs, but people wanted it to do more. Netscape envisioned that web pages should be more dynamic in nature. If users are not able to engage with HTMLs, browsers will end up becoming boring pieces of software, they figured.That’s when Brendan Eich came into the picture. He was contracted in 1995 by Netscape Communications to develop a language which would have a low learning curve, so that anyone would be able to write functionalities with it. He developed the language in just 10 days and named it Mocha. A working prototype of Mocha was integrated in the Netscape Browser in May 1995, renaming the language to LiveScript and later in December 1995, it was renamed again, this time as JavaScript. The marketing team at Netscape chose to call it "JavaScript" as Java was extremely popular at that time. With the popularity of Netscape Navigator, Microsoft wished to capture the browser market and developed Internet Explorer with a scripting language named JScript. For a long time, there was no common standard formed for JavaScript, resulting in huge cross browser compatibility issues. Finally, in 1997, Netscape invited ECMA (European Computer Manufacturing Association) to take the responsibility of forming a specification for JavaScript.Since then, the ECMA has released updated specifications for JavaScript regularly and browsers try to follow these specifications in their implementation of JavaScript engine.Fact Check: Today, Brendan Eich is the CEO of Brave Software which builds a privacy oriented, chromium-based browser named Brave.Fact Check: Netscape Navigator later became the foundation stone for Mozilla Firefox. They retained the same name for their JavaScript engine "Spider Monkey" which was part of the Netscape navigator.Need of Framework With the ECMAScript specifications in place, developers began to use JavaScript  to make the HTML page much more dynamic using JavaScript. However, there were still a few developers who preferred to write big client-side functionality with JavaScript, owing to low performance of browser and JavaScript engines. Perhaps, the industry had a more a server-side performance focus in that era. Then, as computers became more powerful, browser performance improved and JavaScript engines evolved, developers started moving client-side logic to browser using JavaScript.Once developers started writing more and more JavaScript, the community felt the need to write logic in a more structured and scalable manner, so as to be more understandable, readable, manageable and less error prone. The need for a framework in JavaScript was clearly felt.Many frameworks like Dojo, Backbone, Ember and AngularJS eventually emerged within their own communities, which tried to solve problems in their unique way. Collectively, this has helped the whole JS community to move forward towards a more scalable and maintainable web application. ReactJS In 2011, Codebase for Facebook Ads was getting bigger. Developers began to face maintenance issues with it and it was getting harder to add new features in an efficient way. That's when Facebook engineer, Jordan Walke, built a prototype for an efficient application UI. This marked the birth of ReactJS, initially called FaxJS. Later, when Instagram was acquired by Facebook, the folks at Instagram wanted to adopt this framework. Pete Hunt and Jordan Walke then improved, decoupled the library and made it open source as ReactJS in 2013. Since then ReactJS has gone through many changes. The latest version of ReactJS in 2020 is currently 16.13. ReactJS follows component-based architecture and encourages developers to think in terms of small, composable components. Interestingly, this methodology is aligned with an efficient approach for solving any problem in life: the first step to solve a big problem is to break it down into multiple smaller sub problems. Once you have a solution for each sub-problem, you can then add it up to get the overall solution. This can be applied to all problems, big or small. ReactJS asks developer to adopt a problem-solving approach like this to build any UI. It must be noted that ReactJS does not aim to solve each and every problem of building a web application. Rather, it has a narrow focus and a limited scope to solve the one core problem of web development around how to efficiently updating the UI/views.When ReactJS was open sourced in the JSConf 2013, the ideas and changes that ReactJS was proposing were not very well received. For instance, although two-way binding was very popular, ReactJS went ahead with one way data flow. In another example, writing HTML inside JS was considered a bad practice, but ReactJS still wanted to use JSX. All these ideas initially attracted a lot of criticism from the web developer community. In time, however, developers started using it and found it easy to build components efficiently. So, ReactJS now solved the one problem around updating views. But what about all the problems in web development? An ecosystem began to emerge to address the other problems along with ReactJS. Libraries like Redux and React-Router came to life, making ReactJS a complete web framework, although this meant that there would be a dependency on multiple libraries. The ease of using ReactJS trumped all the negative points of the framework and this is what continues to make it a very popular library in web development. In 2020, ReactJS has 50K plus stars on Github and is downloaded 6 million times per week. The ReactJS ecosystem continues to grow steadily; React Native recently bought ReactJS to build cross mobile platform apps. Libraries like Gatsby and NextJS encourage developers to use ReactJS on server and provide benefits of server-side rendering without much hassle. ReactJS has also stood out in multiple developer surveys such as the State of JavaScript. Main design concepts in ReactJS Main design concepts in ReactJSDeclarative, composable, reusable componentsReactJS motivates developers to write small components and reuse the same component at multiple places. Re-usability of components greatly speeds up the overall development and results in less amount of code. Less code is always better because it is less prone to errors. ReactJS encourages developers to write composable components which can be wrapped around any other React component to provide special functionality, thus discouraging the writing of components that do too many things. ReactJS always encourages developers to break their problem into smaller problems, solve the smaller problems first and then combine them to present the overall solution. Less functionality in components always leads to less error prone components. ReactJS encourages developers to write clean, readable, and maintainable code. This is why it emphasizes writing declarative components, which make a codebase easier to read and understand by fellow developers.Declarative, composable components looks a lot like HTML in JS. Instead of standard HTML tags, we have React components as tags. This similarity to standard web semantics is what makes JS somewhat familiar to developers starting out. Reactive Updates Writing static HTML is no fun and it can be said that JavaScript was born to bring interactivity to web pages. ReactJS helps developer to add functionalities in components with which the user can interact and see the results. ReactJS allows developers to attach a state to component and whenever the state of components changes, the component efficiently re-renders itself to produce an updated view. Now, the state of the component can be changed by clicking a button, entering text into the input box or any other part of the component triggering an event. The React component listens to these events and acts accordingly. Updating the whole component UI seems like a terrible idea, but ReactJS has implemented this terrible idea wonderfully by doing it efficiently. In-memory DOM representation ReactJS is able to efficiently update views by keeping a DOM representation in memory known as virtual DOM. Upcoming updates always compare the new DOM with an older copy of the DOM and based on the difference, it figures out the actual DOM elements which need to be updated on the UI. Reducing the number of DOM manipulations makes ReactJS faster. What this means is that writing smaller React components will take up less memory to store DOM representations (Virtual DOM) and ultimately, this results in better performance. Features of ReactJS Main features of ReactJSJSX and Why is it needed When ReactJS was released, it was mentioned in documentation that it is recommended to use JSX along with ReactJS. Now, what is JSX? and do i really need another library to use the ReactJS library? So, let us see how a simple ReactJS component looks without JSX: import React from "react";  function Greeting({ name }) {    return React.createElement("h1", null, `Hello ${name}`);  }  ReactDOM.render(  React.createElement("Greeting", { name: "Gully Boy" }, null),  document.getElementById("root")  ); There is no way the above code looks like a declarative component. The truth is JavaScript does not understand HTML or XML like tags. That is why we need someone to do that conversion for us. Here enters JSX, also known as a syntax extension for JavaScript. With JSX, the above Greeting React component will look something like this: import React from "react";  function Greeting({ name }) {    return {`Hello ${name}`};  }  ReactDOM.render(<Greeting name="Gully Boy" />, document.getElementById("root")); JSX actually makes ReactJS code more readable and understandable. You can assume this as a templating library which converts HTML looking syntax into ReactJS element JS code by calling createElement(). Virtual DOM ReactJS has made the term, 'VDOM' or virtual DOM very popular in the JavaScript community. Web browsers have provided APIs to interact with DOM to make our web page dynamic. One can dynamically add or remove nodes in the web page by using these APIs. But interacting with these APIs was very slow, as changing node triggers re-layout and re-paint event for sub-tree. Although the entire subtree is re-rendered (diffing stops when an element type has been modified and subtree is freshly rendered), even in case of virtual DOM reconciliation, the advantage that React offers is that the developer is freed from figuring out which part of DOM really requires updates - the diffing and reconciliation algorithm takes care of it.  React has thus provided a way to reduce the number to change in DOM using virtual DOM. The VDOM is a JavaScript object which contains information of DOM sub tree. We can also call this an object representation of DOM. React uses this object to compare subsequent modification and figure out the minimum number of modifications needed to make in browser DOM to get the desired result. ReactJS claims that the wonderful performance of their library is because of the algorithm they use to compare the virtual DOM. React Native React native is another popular library which is used to build cross platform mobile applications using JavaScript. Before ReactJS, Cordova and ionic were some frameworks which were very popular to build mobile applications using JavaScript. However, these applications did not perform very well. React native uses popular component-based concepts of ReactJS and provides a way to build an efficient mobile application. React native converts JS code into native platform code to run in mobile devices. This approach has improved the performance of mobile applications by a great deal in comparison to other frameworks like ionic. With React Native, ReactJS has now become a very popular library to build UI on any platform. ReactJS: Here to stay Over the past decade, the JavaScript community has seen tremendous changes in language within the developer community. It has seen a lot of new ideas and terms surface in the form of libraries. Developers are building and sharing their work with rest of the world quite frequently and every other day, implementations are open sourced on Github. These new ideas and the problem solving approach continues to help the JavaScript ecosystem to evolve and become better. Prior to ReactJS, JQuery was very popular and was the default library for any web project involving DOM manipulation. With AngularJS and other MVC libraries, we were encouraged to think about a problem in terms of Modal, View and Controller. People have always sought to figure out an approach that can solve the problem. And structuring a solution in a scalable manner is not a new challenge either. We have already implemented scalable solutions at server-side, and they are performing quite well. ReactJS now brings the same pattern to the front-end, where the final output is a UI. To implement this, we break the problem into smaller sub-problems and write solutions for them. This is the basic mental model to solve all UI problems and ReactJS focuses on the same. New ideas in the JavaScript community help the community move forward and eventually, the best solutions become part of the standard JS (ECMAScript). ES modules, promises and some lodash utilities are examples of this. When a library moves in the same general direction as the web, it is bound to be used by a large community. Developers will use these solutions until new specifications are finalized and browsers adopting new specifications. Interim, people will use the feature in the form of third party library.So, is ReactJS moving in the right direction? I would say yes. ReactJS is evolving right along the evolving standards of JavaScript. The front-end community is leaning more towards concepts of functional programming rather than object-oriented methodology. In a similar direction, ReactJS continues to move towards a functional programming pattern. ReactJS has introduced hooks in version 16.8, which encourages developer to build more and more functional components instead of class-based components. Hook does not even work with class-based component. Understanding well that it sometimes becomes a hectic task to figure out which library one should choose to handle state management, ContextAPI and useReducer hooks have been introduced, which help in managing state in small applications much better. Today, with the help of ContextAPI and useReducer hooks, you can build an application without using any other library like Redux. This, however, does not mean that you should stop using Redux as it has its own benefits.Component based architecture is also aligned with the standard web components support in browsers, which allow developers to write non-standard HTML tags in code. In short, ReactJS has made the community become familiar with some of the upcoming web standards. For this reason, I feel that conceptually, ReactJS is going to stay with the community for long. Many big companies like Facebook, Microsoft and AirBnB are supporting the direction and concepts of ReactJS, thus adding credibility to the library. With many big brains backing the library, the ReactJS community looks poised for growth. With no perfect solution to all the problems in web development in sight, the best option is to move forward with whatever is available at the moment. In the JavaScript community too, there is an effort to figure out an alternate to ReactJS such as VueJS and Svelte. Perhaps, ReactJS will get replaced by some other library in the future. However, the basic idea of creating smaller, reusable components is here to stay.Whatever framework we learn, it is most important to grasp the basic idea behind the library. It is this idea or design pattern that is going to remain for good. It may appear in front of you in a different form and shape, but the idea will remain forever. 

Why ReactJS is taking over Frontend Development

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Why ReactJS is taking over Frontend Development

History of JavaScript 

Today, we see JavaScript used pretty much everywhere. For the seventh year in a row, we see it ranking as the most popular and widely used programming language, a good 67.8% of developers having used it in 2019. 

JavaScript is used to build 95.2% (1.52 billion) websites today, including Facebook and YouTube and some of the most popular and useful apps such as Google Maps and eBay. 

Let’s take a closer look at what JavaScript is, how and why it was created, and how it seems to be taking over front-end development. 

It all began in the late 90s when Netscape Navigator, a popular browser was launched by Netscape Communication. In the initial days of Netscape, it was just a software which was able to render static HTMLs, but people wanted it to do more. Netscape envisioned that web pages should be more dynamic in nature. If users are not able to engage with HTMLs, browsers will end up becoming boring pieces of software, they figured.

That’s when Brendan Eich came into the picture. He was contracted in 1995 by Netscape Communications to develop a language which would have a low learning curve, so that anyone would be able to write functionalities with it. He developed the language in just 10 days and named it Mocha. A working prototype of Mocha was integrated in the Netscape Browser in May 1995, renaming the language to LiveScript and later in December 1995, it was renamed again, this time as JavaScript

The marketing team at Netscape chose to call it "JavaScript" as Java was extremely popular at that time. With the popularity of Netscape Navigator, Microsoft wished to capture the browser market and developed Internet Explorer with a scripting language named JScript. For a long time, there was no common standard formed for JavaScript, resulting in huge cross browser compatibility issues. Finally, in 1997, Netscape invited ECMA (European Computer Manufacturing Association) to take the responsibility of forming a specification for JavaScript.

Since then, the ECMA has released updated specifications for JavaScript regularly and browsers try to follow these specifications in their implementation of JavaScript engine.

Fact Check: Today, Brendan Eich is the CEO of Brave Software which builds a privacy oriented, chromium-based browser named Brave.

Fact Check: Netscape Navigator later became the foundation stone for Mozilla Firefox. They retained the same name for their JavaScript engine "Spider Monkey" which was part of the Netscape navigator.

Need of Framework 

With the ECMAScript specifications in place, developers began to use JavaScript  to make the HTML page much more dynamic using JavaScript. However, there were still a few developers who preferred to write big client-side functionality with JavaScript, owing to low performance of browser and JavaScript engines. Perhaps, the industry had a more a server-side performance focus in that era. Then, as computers became more powerful, browser performance improved and JavaScript engines evolved, developers started moving client-side logic to browser using JavaScript.

Once developers started writing more and more JavaScript, the community felt the need to write logic in a more structured and scalable manner, so as to be more understandable, readable, manageable and less error prone. The need for a framework in JavaScript was clearly felt.

Many frameworks like Dojo, Backbone, Ember and AngularJS eventually emerged within their own communities, which tried to solve problems in their unique way. Collectively, this has helped the whole JS community to move forward towards a more scalable and maintainable web application. 

ReactJS 

In 2011, Codebase for Facebook Ads was getting bigger. Developers began to face maintenance issues with it and it was getting harder to add new features in an efficient way. That's when Facebook engineer, Jordan Walke, built a prototype for an efficient application UI. This marked the birth of ReactJS, initially called FaxJS. Later, when Instagram was acquired by Facebook, the folks at Instagram wanted to adopt this framework. Pete Hunt and Jordan Walke then improved, decoupled the library and made it open source as ReactJS in 2013. Since then ReactJS has gone through many changes. The latest version of ReactJS in 2020 is currently 16.13. 

ReactJS follows component-based architecture and encourages developers to think in terms of small, composable components. Interestingly, this methodology is aligned with an efficient approach for solving any problem in life: the first step to solve a big problem is to break it down into multiple smaller sub problems. Once you have a solution for each sub-problem, you can then add it up to get the overall solution. This can be applied to all problems, big or small. ReactJS asks developer to adopt a problem-solving approach like this to build any UI. It must be noted that ReactJS does not aim to solve each and every problem of building a web application. Rather, it has a narrow focus and a limited scope to solve the one core problem of web development around how to efficiently updating the UI/views.

When ReactJS was open sourced in the JSConf 2013, the ideas and changes that ReactJS was proposing were not very well received. For instance, although two-way binding was very popular, ReactJS went ahead with one way data flow. In another example, writing HTML inside JS was considered a bad practice, but ReactJS still wanted to use JSX. All these ideas initially attracted a lot of criticism from the web developer community. In time, however, developers started using it and found it easy to build components efficiently. 

So, ReactJS now solved the one problem around updating views. But what about all the problems in web development? An ecosystem began to emerge to address the other problems along with ReactJS. Libraries like Redux and React-Router came to life, making ReactJS a complete web framework, although this meant that there would be a dependency on multiple libraries. The ease of using ReactJS trumped all the negative points of the framework and this is what continues to make it a very popular library in web development. In 2020, ReactJS has 50K plus stars on Github and is downloaded 6 million times per week. 

The ReactJS ecosystem continues to grow steadily; React Native recently bought ReactJS to build cross mobile platform apps. Libraries like Gatsby and NextJS encourage developers to use ReactJS on server and provide benefits of server-side rendering without much hassle. ReactJS has also stood out in multiple developer surveys such as the State of JavaScript

Main design concepts in ReactJS 

Main design concepts in ReactJS Main design concepts in ReactJS

Declarative, composable, reusable components

ReactJS motivates developers to write small components and reuse the same component at multiple places. Re-usability of components greatly speeds up the overall development and results in less amount of code. Less code is always better because it is less prone to errors. 

ReactJS encourages developers to write composable components which can be wrapped around any other React component to provide special functionality, thus discouraging the writing of components that do too many things. ReactJS always encourages developers to break their problem into smaller problems, solve the smaller problems first and then combine them to present the overall solution. Less functionality in components always leads to less error prone components. 

ReactJS encourages developers to write clean, readable, and maintainable code. This is why it emphasizes writing declarative components, which make a codebase easier to read and understand by fellow developers.

Declarative, composable components looks a lot like HTML in JS. Instead of standard HTML tags, we have React components as tags. This similarity to standard web semantics is what makes JS somewhat familiar to developers starting out. 

Reactive Updates 

Writing static HTML is no fun and it can be said that JavaScript was born to bring interactivity to web pages. ReactJS helps developer to add functionalities in components with which the user can interact and see the results. ReactJS allows developers to attach a state to component and whenever the state of components changes, the component efficiently re-renders itself to produce an updated view. Now, the state of the component can be changed by clicking a button, entering text into the input box or any other part of the component triggering an event. The React component listens to these events and acts accordingly. Updating the whole component UI seems like a terrible idea, but ReactJS has implemented this terrible idea wonderfully by doing it efficiently. 

In-memory DOM representation 

ReactJS is able to efficiently update views by keeping a DOM representation in memory known as virtual DOM. Upcoming updates always compare the new DOM with an older copy of the DOM and based on the difference, it figures out the actual DOM elements which need to be updated on the UI. Reducing the number of DOM manipulations makes ReactJS faster. What this means is that writing smaller React components will take up less memory to store DOM representations (Virtual DOM) and ultimately, this results in better performance. 

Features of ReactJS 

Features of ReactJS Main features of ReactJSJSX and Why is it needed 

When ReactJS was released, it was mentioned in documentation that it is recommended to use JSX along with ReactJS. Now, what is JSX? and do i really need another library to use the ReactJS library? So, let us see how a simple ReactJS component looks without JSX: 

import React from "react"; 
function Greeting({ name }) { 
  return React.createElement("h1", null, `Hello ${name}`); 
} 
ReactDOM.render( 
React.createElement("Greeting", { name: "Gully Boy" }, null), 
document.getElementById("root") 
); 

There is no way the above code looks like a declarative component. The truth is JavaScript does not understand HTML or XML like tags. That is why we need someone to do that conversion for us. Here enters JSX, also known as a syntax extension for JavaScript. With JSX, the above Greeting React component will look something like this: 

import React from "react"; 
function Greeting({ name }) { 
  return {`Hello ${name}`}; 
} 
ReactDOM.render(<Greeting name="Gully Boy" />, 
document.getElementById("root")); 

JSX actually makes ReactJS code more readable and understandable. You can assume this as a templating library which converts HTML looking syntax into ReactJS element JS code by calling createElement(). 

Virtual DOM 

ReactJS has made the term, 'VDOM' or virtual DOM very popular in the JavaScript community. Web browsers have provided APIs to interact with DOM to make our web page dynamic. One can dynamically add or remove nodes in the web page by using these APIs. But interacting with these APIs was very slow, as changing node triggers re-layout and re-paint event for sub-tree. Although the entire subtree is re-rendered (diffing stops when an element type has been modified and subtree is freshly rendered), even in case of virtual DOM reconciliation, the advantage that React offers is that the developer is freed from figuring out which part of DOM really requires updates - the diffing and reconciliation algorithm takes care of it.  

React has thus provided a way to reduce the number to change in DOM using virtual DOM. The VDOM is a JavaScript object which contains information of DOM sub tree. We can also call this an object representation of DOM. React uses this object to compare subsequent modification and figure out the minimum number of modifications needed to make in browser DOM to get the desired result. ReactJS claims that the wonderful performance of their library is because of the algorithm they use to compare the virtual DOM. 

React Native 

React native is another popular library which is used to build cross platform mobile applications using JavaScript. Before ReactJS, Cordova and ionic were some frameworks which were very popular to build mobile applications using JavaScript. However, these applications did not perform very well. React native uses popular component-based concepts of ReactJS and provides a way to build an efficient mobile application. React native converts JS code into native platform code to run in mobile devices. This approach has improved the performance of mobile applications by a great deal in comparison to other frameworks like ionic. With React Native, ReactJS has now become a very popular library to build UI on any platform. 

ReactJS: Here to stay 

Over the past decade, the JavaScript community has seen tremendous changes in language within the developer community. It has seen a lot of new ideas and terms surface in the form of libraries. Developers are building and sharing their work with rest of the world quite frequently and every other day, implementations are open sourced on Github. 

These new ideas and the problem solving approach continues to help the JavaScript ecosystem to evolve and become better. Prior to ReactJS, JQuery was very popular and was the default library for any web project involving DOM manipulation. With AngularJS and other MVC libraries, we were encouraged to think about a problem in terms of Modal, View and Controller. 

People have always sought to figure out an approach that can solve the problem. And structuring a solution in a scalable manner is not a new challenge either. We have already implemented scalable solutions at server-side, and they are performing quite well. ReactJS now brings the same pattern to the front-end, where the final output is a UI. To implement this, we break the problem into smaller sub-problems and write solutions for them. This is the basic mental model to solve all UI problems and ReactJS focuses on the same. 

New ideas in the JavaScript community help the community move forward and eventually, the best solutions become part of the standard JS (ECMAScript). ES modules, promises and some lodash utilities are examples of this. 

When a library moves in the same general direction as the web, it is bound to be used by a large community. Developers will use these solutions until new specifications are finalized and browsers adopting new specifications. Interim, people will use the feature in the form of third party library.

So, is ReactJS moving in the right direction? 

I would say yes. ReactJS is evolving right along the evolving standards of JavaScript. The front-end community is leaning more towards concepts of functional programming rather than object-oriented methodology. In a similar direction, ReactJS continues to move towards a functional programming pattern. 

ReactJS has introduced hooks in version 16.8, which encourages developer to build more and more functional components instead of class-based components. Hook does not even work with class-based component. Understanding well that it sometimes becomes a hectic task to figure out which library one should choose to handle state management, ContextAPI and useReducer hooks have been introduced, which help in managing state in small applications much better. Today, with the help of ContextAPI and useReducer hooks, you can build an application without using any other library like Redux. This, however, does not mean that you should stop using Redux as it has its own benefits.

Component based architecture is also aligned with the standard web components support in browsers, which allow developers to write non-standard HTML tags in code. In short, ReactJS has made the community become familiar with some of the upcoming web standards. For this reason, I feel that conceptually, ReactJS is going to stay with the community for long. 

Many big companies like Facebook, Microsoft and AirBnB are supporting the direction and concepts of ReactJS, thus adding credibility to the library. With many big brains backing the library, the ReactJS community looks poised for growth. 

With no perfect solution to all the problems in web development in sight, the best option is to move forward with whatever is available at the moment. In the JavaScript community too, there is an effort to figure out an alternate to ReactJS such as VueJS and Svelte. Perhaps, ReactJS will get replaced by some other library in the future. However, the basic idea of creating smaller, reusable components is here to stay.

Whatever framework we learn, it is most important to grasp the basic idea behind the library. It is this idea or design pattern that is going to remain for good. It may appear in front of you in a different form and shape, but the idea will remain forever. 

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The synthetic event object has properties mentioned below:  Boolean isTrusted  DOMEvent nativeEvent number timeStamp   void preventDefault() number eventPhase Synthetic events provide an interface and reduce browser inconsistencies and the event contains required information for its propagation to work. Synthetic event is reused for performance reasons in the browser, A synthetic event is a cross-browser wrapper around the browser’s native event it has the same interface as the native event. Synthetic events are delegated to the document node. Therefore native events are triggered first and the events bubble up to document, after which the synthetic events are triggered. The synthetic event object will be reused and all the properties will be nullified after the event callback has been invoked and this is for performance reasons.The workflow of synthetic event in react is:    Element ---- > Event ---- > synthetic event  ---- > handler(e)                                |                                                      |                                |  _______  Component ________|  umber timeStamp The Basics of React Event Handling Let’s explore how to handle events in react and we will showcase the click event and how it holds good for other types of events. Let’s start with functional components by creating a  file as clickAppHandler.js.In this file let’s create a  functional component  as shown below                        Import React from ‘...react’                         function clickAppHandler() {                                function clickHandler() {                                        console.log(‘clicked’)                                         }                                  return (                                                                                  Click                                                                          )                         }                       export default clickAppHandler  When onClick event triggers clickHandler function is called as shown below and when you click the button console will print the string “clicked” After this you need the add a component in the app component. In our code above you can see on click we pass the function as event handler and you will notice that we haven't added parentheses as it becomes a function, and we do not want that and we want handler to be a function not a function call. When a new component is rendered its event handler functions are added to the mapping maintained by the react.When the event is triggered and it hits and DOM object ,react maps the event to the handler, if it matches it calls the handler. The event handling in react is declarative and the advantage of declarative way to handlers is that they are part of the User interface structure.  Let’s take a look at event handling in class components                       Import React, { Component } from ‘...react’                         class TestApp extends Component {                              clickHandler() {                                  console.log(“clicked”)                                }                                render(){                                      return(                                                                                     Click me                                                                                 )                                 }                            }                       export default TestApp You cannot return false to prevent default behaviour in React. You must call preventDefault explicitly.  In HTML it looks like below:    Click Output: It will print “Clicked”  And in React, like this:  function clickHandle(e) {       e.preventDefault();       console.log(“Handled”);   }  Click  Output : console will print “Handled”  There are some  event handlers triggered by an event in the bubbling phase which is the same as with the normal DOM API; simply attach a handler to an eventual parent of an element and any events triggered on that element will bubble to the parent as long as it's not stopped via stopPropagation along the way   Click me  Below are some of the event handlers triggered in the bubbling phase:  MouseEvents           onClick           onDrag          onDoubleClick Keyboard Events                    onKeyDown                    onKeyPress                    onKeyUp Focus Events                  onFocus   onBlur To capture an event handler for the capture phase, append capture to the event name. For example, instead of using onClick, use onClickCapture to handle the click event.  Capture event example:                  Click me    Additional ExamplesExample1                       Import React from ‘...react’                         function clickAppHandler() {                                function clickHandler() {                                        console.log(‘clicked’)                                         }                                  return (                                                                                  Click                                                                          )                         }                       export default clickAppHandler   Example2       This example is along with HTML in a single file                                                            Events                               function testApp (){                        alert((“Hello Event”);                                                   test Clicked                  test double Clicked                     Adding Events: Below example is how you add an event. Highlighted in bold                      Import React from ‘...react’                         function clickAppHandler() {                                function clickHandler() {                                        console.log(‘clicked’)                                         }                                  return (                                                                                  Click                                                                          )                         }                       export default clickAppHandler  Passing Arguments to Event HandlerThere are two ways arguments are passed to event handler  Arrow function                    this.handleClick(id,e)}>Click                onClick is the event                e is the event object                 id can be state or props or some data Bind method      Click  In this case event object is automatically passed In both methods e represents the react event and its passed after the ID as second argument,With an arrow function this event e is passed explicitly but with bind method its automatically passed.                                     Import React,{ Component } from “react”;                                         class TestApp extends Component {                                           state = {                                                       id: 2,                                                      Name: “TestApp Dummy”                                                };                                                             //arrow function                                                 handleClick = (id,e) => {                                                       console.log(id);                                                       console.log(e);                                                  };                                               handleArg = (e) => { this.handleClick(this.state.id,e);}                                                          render() {     return (                    TestApp,{this.state.name}            onClick={this.handleArg}>Display            );   }  }  The react event is an object and obtained from react. Instead of creating a separate function for passing argument, you can directly pass the anonymous arrow function as shown in the render function below:     render() {        return (                                                                                                       TestApp,{this.state.name}                                                {                           this.handleClick(this.state.id,e);                                                               }}>Display                                                                                                         );                                                 }                                            }    Output:   click on button  “TestApp Dummy “                   Let’s see only how bind method looks like in the render function    render() {                                         return (                                                                                                 TestApp,{this.state.name}                                                   Display                                                                                                       );                                                  }                                              } Output: this will display the h1 tag and when you click the button handleClick function gets invoked and the console will display id of the state object as shown above. Building a Practice to Thoroughly Understand Events This blog focuses on event handling, which in turn teaches about event handlers declared in JSX markup.This approach helps in tracking down the element mapped with events in an easy way.  We also learned how to handle multiple event handlers in a single element by using JSX attributes.we also learned about ways to bind event handler and  parameter values. Then we learned about synthetic events which are abstractions around native events. The best way you can retain this learning is by practicing more and tackling the complexities that may arise as you practice. You can find several tutorials on the internet or share your questions with us here. Happy learning! 
5355
Handling React Events - A Detailed Guide

Event handling essentially allows the user to inte... Read More

MongoDB Query Document Using Find() With Example

MongoDB's find() method selects documents from a collection or view and returns a cursor to those documents. There are two parameters in this formula: query and projection.Query – This is an optional parameter that specifies the criteria for selection. In simple terms, a query is what you want to search for within a collection.Projection – This is an optional parameter that specifies what should be returned if the query criteria are satisfied. In simple terms, it is a type of decision-making that is based on a set of criteria.MongoDB's Flexible SchemaA NoSQL database, which stands for "not only SQL," is a way of storing and retrieving data that is different from relational databases' traditional table structures (RDBMS).When storing large amounts of unstructured data with changing schemas, NoSQL databases are indeed a better option than RDBMS. Horizontal scaling properties of NoSQL databases allow them to store and process large amounts of data.These are intended for storing, retrieving, and managing document-oriented data, which is frequently stored in JSON format (JavaScript Object Notation). Document databases, unlike RDBMSs, have a flexible schema that is defined by the contents of the documents.MongoDB is one of the most widely used open-source NoSQL document databases. MongoDB is known as a 'schemaless' database because it does not impose a specific structure on documents in a collection.MongoDB is compatible with a number of popular programming languages. It also offers a high level of operational flexibility because it scales well horizontally, allowing data to be spread or 'sharded' across multiple commodity servers with the ability to add more servers as needed. MongoDB can be run on a variety of platforms, including developer laptops, private clouds, and public clouds.Querying documents using find()MongoDB queries are used to retrieve or fetch data from a MongoDB database. When running a query, you can use criteria or conditions to retrieve specific data from the database.The function db.collection is provided by MongoDB. find() is a function that retrieves documents from a MongoDB database.In MongoDB, the find method is used to retrieve a specific document from the MongoDB collection. In Mongo DB, there are a total of six methods for retrieving specific records.find()findAndModify()findOne()findOneAndDelete()findOneAndReplace()findOneAndUpdate()Syntax:find(query, projection)We can fetch a specific record using the Find method, which has two parameters. If these two parameters are omitted, the find method will return all of the documents in the MongoDB collection.Example:Consider an example of employees with the database of employee_id and employee_name and we will fetch the documents using find() method.First, create a database with the name “employees” with the following code:use employeesNow, create a collection “employee” with:db.createCollection("employee")In the next step we will insert the documents in the database:db.employee.insert([{employee_id: 101, employee_name: "Ishan"}, {employee_id: 102, employee_name: "Bhavesh"}, {employee_id: 103, employee_name: "Madan"}])Find all Documents:To get all the records in a collection, we need to use the find method with an empty parameter. In other words, when we need all the records, we will not use any parameters.db.employee.find()Output in Mongo ShellThe pretty() method can be used to display the results in a formatted manner.Syntax:db.COLLECTION_NAME.find().pretty()Let’s check our documents with pretty() method:Query FiltersWe will see examples of query operations using the db.collection.find() method in mongosh.We will use the employee collection in the employees database.db.employee.insert([{employee_id: 101, employee_name: "Ishan", age: 21, email_id: "ishanjain@gmail.com"}, {employee_id: 102, employee_name: "Bhavesh", age: 22, email_id: "bhaveshg@gmail.com"}, {employee_id: 103, employee_name: "Madan", age: 23, email_id: "madan@gmail.com"}])As we have seen earlier that to select all the documents in the database we pass an empty document as the query filter parameter to the find method.db.employee.find().pretty()Find the first document in a collection:db.employee.findOne()Find a document by ID:db.employee.findOne({_id : ObjectId("61d1ae0b56b92c20b423a5a7")})Find Documents that Match Query Criteriadb.employee.find({“age”: “22”})db.employee.find({"employee_name": "Madan"}).pretty()Sort Results by a Field:db.employee.find().sort({age: 1}).pretty()order by age, in ascending orderdb.employee.find().sort({age: -1}).pretty()order by age, in descending orderAND Conditions:A compound query can specify conditions for multiple fields in the documents in a collection. A logical AND conjunction connects the clauses of a compound query indirectly, allowing the query to select all documents in the collection that meet the specified conditions.In the following example, we will consider all the documents in the employee collection where employee_id equals 101 and age equals 21.db.employee.find({"employee_id": 101, "age": "21" }).pretty()Querying nested fieldsThe embedded or nested document feature in MongoDB is a useful feature. Embedded documents, also known as nested documents, are documents that contain other documents.You can simply embed a document inside another document in MongoDB. Documents are defined in the mongo shell using curly braces (), and field-value pairs are contained within these curly braces.Using curly braces, we can now embed or set another document inside these fields, which can include field-value pairs or another sub-document.Syntax:{ field: { field1: value1, field2: value2 } }Example:We have a database “nested” and in this database we have collection “nesteddoc”.The following documents will insert into the nesteddoc collection.db.nesteddoc.insertMany([ { "_id" : 1, "dept" : "A", "item" : { "sku" : "101", "color" : "red" }, "sizes" : [ "S", "M" ] }, { "_id" : 2, "dept" : "A", "item" : { "sku" : "102", "color" : "blue" }, "sizes" : [ "M", "L" ] }, { "_id" : 3, "dept" : "B", "item" : { "sku" : "103", "color" : "blue" }, "sizes" : "S" }, { "_id" : 4, "dept" : "A", "item" : { "sku" : "104", "color" : "black" }, "sizes" : [ "S" ] } ])Place the documents in the collection now. Also, take a look at the results:As a result, the nesteddoc collection contains four documents, each of which contains nested documents. The find() method can be used to access the collection's documents.db.nesteddoc.find()Specify Equality Condition:In this example, we will select the document from the nesteddoc query where dept equals “A”.db.nesteddoc.find({dept: "A"})Querying ArraysUse the query document {: } to specify an equality condition on an array, where is the exact array to match, including the order of the elements.The following query looks for all documents where the field tags value is an array with exactly two elements, "S" and "M," in the order specified:db.nesteddoc.find( { sizes: ["S", "M"] } )Use the $all operator to find an array that contains both the elements "S" and "M," regardless of order or other elements in the array:db.nested.find( { sizes: { $all: ["S", "M"] } } )Query an Array for an Element:The following example queries for all documents where size is an array that contains the string “S” as one of its elements:db.nesteddoc.find( { sizes: "S" } )Filter conditionsTo discuss the filter conditions, we will consider a situation that elaborates this. We will start by creating a collection with the name “products” and then add the documents to it.db.products.insertMany([ { _id: 1, item: { name: "ab", code: "123" }, qty: 15, tags: [ "A", "B", "C" ] }, { _id: 2, item: { name: "cd", code: "123" }, qty: 20, tags: [ "B" ] }, { _id: 3, item: { name: "ij", code: "456" }, qty: 25, tags: [ "A", "B" ] }, { _id: 4, item: { name: "xy", code: "456" }, qty: 30, tags: [ "B", "A" ] }, { _id: 5, item: { name: "mn", code: "000" }, qty: 20, tags: [ [ "A", "B" ], "C" ] }])To check the documents, use db.products.find():$gt$gt selects documents with a field value greater than (or equal to) the specified value.db.products.find( { qty: { $gt: “20” } } )$gte:$gte finds documents in which a field's value is greater than or equal to (i.e. >=) a specified value (e.g. value.)db.products.find( { qty: { $gte: 20 } } )$lt:$lt selects documents whose field value is less than (or equal to) the specified value.db.products.find( { qty: { $lt: 25 } } )$lte:$lte selects documents in which the field's value is less than or equal to (i.e. =) the specified value.db.products.find( { qty: { $lte: 20 } } )Query an Array by Array Length:To find arrays with a specific number of elements, use the $size operator. For example, the following selects documents with two elements in the array.db.products.find( { "tags": {$size: 2} } )ProjectionIn MongoDB, projection refers to selecting only the data that is required rather than the entire document's data. If a document has five fields and you only want to show three of them, select only three of them.The find() method in MongoDB accepts a second optional parameter, which is a list of fields to retrieve, as explained in MongoDB Query Document. When you use the find() method in MongoDB, it displays all of a document's fields. To prevent this, create a list of fields with the values 1 or 0. The value 1 indicates that the field should be visible, while 0 indicates that it should be hidden.Syntax:db.COLLECTION_NAME.find({},{KEY:1})Example:We will consider the previous example of products collection. Run the below command on mongoshell to learn how projection works:db.products.find({},{"tags":1, _id:0})Keep in mind that the _id field is always displayed while executing the find() method; if you do not want this field to be displayed, set it to 0.Optimized FindingsTo retrieve a document from a MongoDB collection, use the Find method.Using the Find method, we can retrieve specific documents as well as the fields that we require. Other find methods can also be used to retrieve specific documents based on our needs.By inserting array elements into the query, we can retrieve specific elements or documents. To retrieve data for array elements from the collection in MongoDB, we can use multiple query operators.
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MongoDB Query Document Using Find() With Example

MongoDB's find() method selects documents from a c... Read More

Implementing MongoDb Map Reduce using Aggregation

Algorithms and applications in today's data-driven market collect data about people, processes, systems, and organisations 24 hours a day, seven days a week, resulting in massive amounts of data. The problem is figuring out how to process this massive amount of data efficiently without sacrificing valuable insights.What is Map Reduce? The MapReduce programming model comes to the rescue here. MapReduce, which was first used by Google to analyse its search results, has grown in popularity due to its ability to split and process terabytes of data in parallel, generating results faster. A (Key,value) pair is the basic unit of information in MapReduce. Before feeding the data to the MapReduce model, all types of structured and unstructured data must be translated to this basic unit. The MapReduce model, as the name implies, consists of two distinct routines: the Map-function and the Reduce-function.  MapReduce is a framework for handling parallelizable problems across huge files using a huge number of devices (nodes), which are collectively referred to as a cluster (if all nodes are on the same local network and use similar hardware) or a grid (if the nodes are shared across geographically and administratively distributed systems, and use more heterogeneous hardware).  When data stored in a filesystem (unstructured) or a database(structured) is processed, MapReduce can take advantage of data's locality, processing it close to where it's stored to reduce communication costs. Typically, a MapReduce framework (or system) consists of three operations: Map: Each worker node applies the map function to local data and saves the result to a temporary storage. Only one copy of the redundant input data is processed by a master node. Shuffle: worker nodes redistribute data based on output keys (produced by the map function), ensuring that all data associated with a single key is stored on the same worker node. Reduce: each group of output data is now processed in parallel by worker nodes, per key. This article will walk you through the Map-Reduce model's functionality step by step. Map Reduce in MongoDB The map-reduce operation has been deprecated since MongoDB 5.0. An aggregation pipeline outperforms a map-reduce operation in terms of performance and usability. Aggregation pipeline operators like $group, $merge, and others can be used to rewrite map-reduce operations. Starting with version 4.4, MongoDB provides the $accumulator and $function aggregation operators for map-reduce operations that require custom functionality. In JavaScript, use these operators to create custom aggregation expressions. The map and reduce functions are the two main functions here. As a result, the data is independently mapped and reduced in different spaces before being combined in the function and saved to the specified new collection. This mapReduce() function was designed to work with large data sets only. You can perform aggregation operations like max and avg on data using Map Reduce, which is similar to groupBy in SQL. It works independently and in parallel on data. Implementing Map Reduce with Mongosh (MongoDB Shell)  The db.collection.mapReduce() method in mongosh is a wrapper for the mapReduce command. The examples that follow make use of the db.collection.mapReduce(). Example: Create a collection ‘orders’ with these documents: db.orders.insertMany([     { _id: 1, cust_id: "Ishan Jain", ord_date: new Date("2021-11-01"), price: 25, items: [ { sku: "oranges", qty: 5, price: 2.5 }, { sku: "apples", qty: 5, price: 2.5 } ], status: "A" },     { _id: 2, cust_id: "Ishan Jain", ord_date: new Date("2021-11-08"), price: 70, items: [ { sku: "oranges", qty: 8, price: 2.5 }, { sku: "chocolates", qty: 5, price: 10 } ], status: "A" },     { _id: 3, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-08"), price: 50, items: [ { sku: "oranges", qty: 10, price: 2.5 }, { sku: "pears", qty: 10, price: 2.5 } ], status: "A" },     { _id: 4, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-18"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },     { _id: 5, cust_id: "Bhavesh Galav", ord_date: new Date("2021-11-19"), price: 50, items: [ { sku: "chocolates", qty: 5, price: 10 } ], status: "A"},     { _id: 6, cust_id: "Madan Parmar", ord_date: new Date("2021-11-19"), price: 35, items: [ { sku: "carrots", qty: 10, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" },     { _id: 7, cust_id: "Madan Parmar", ord_date: new Date("2021-11-20"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },     { _id: 8, cust_id: "Abhresh", ord_date: new Date("2021-11-20"), price: 75, items: [ { sku: "chocolates", qty: 5, price: 10 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" },     { _id: 9, cust_id: "Abhresh", ord_date: new Date("2021-11-20"), price: 55, items: [ { sku: "carrots", qty: 5, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 }, { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },     { _id: 10, cust_id: "Abhresh", ord_date: new Date("2021-11-23"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" }  ]) Apply a map-reduce operation to the orders collection to group them by cust_id, then add the prices for each cust_id: To process each input document, define the map function: this refers the document that the map-reduce operation is processing in the function. For each document, the function maps the price to the cust_id and outputs the cust_id and price. var mapFunction1 = function() {emit(this.cust_id, this.price);}; With the two arguments keyCustId and valuesPrices, define the corresponding reduce function: The elements of the valuesPrices array are the price values emitted by the map function, grouped by keyCustId. The valuesPrice array is reduced to the sum of its elements by this function. var reduceFunction1 = function(keyCustId, valuesPrices) {return Array.sum(valuesPrices);};Apply the mapFunction1 map function and the reduceFunction1 reduce function to all documents in the orders collection: db.orders.mapReduce(mapFunction1,reduceFunction1,{ out: "map_reduce_example" }) The results of this operation are saved in the map_reduce_example collection. If the map_reduce_example collection already exists, the operation will overwrite its contents with the map-reduce operation's results. Check the map_reduce_example collection to verify: db.map_reduce_example.find().sort( { _id: 1 } ) Aggregation Alternative:You can rewrite the map-reduce operation without defining custom functions by using the available aggregation pipeline operators: db.orders.aggregate([{$group: { _id:"$cust_id",value:{$sum: "$price" } } },{ $out: "agg_alternative_1" }]) Check the agg_alternative_1 collection to verify: db.agg_alternative_1.find().sort( { _id: 1 } )Implementing Map Reduce with Java Consider the collection car and insert the following documents in it. db.car.insert( [ {car_id:"c1",name:"Audi",color:"Black",cno:"H110",mfdcountry:"Germany",speed:72,price:11.25}, {car_id:"c2",name:"Polo",color:"White",cno:"H111",mfdcountry:"Japan",speed:65,price:8.5}, {car_id:"c3",name:"Alto",color:"Silver",cno:"H112",mfdcountry:"India",speed:53,price:4.5}, {car_id:"c4",name:"Santro",color:"Grey",cno:"H113",mfdcountry:"Sweden",speed:89,price:3.5} , {car_id:"c5",name:"Zen",color:"Blue",cno:"H114",mfdcountry:"Denmark",speed:94,price:6.5} ] ) You will get an output like this:  Let's now write the map reduce function on a collection of cars, grouping them by speed and classifying them as overspeed cars.  var speedmap = function (){  var criteria;  if ( this.speed > 70 ) {criteria = 'overspeed';emit(criteria,this.speed);}}; Based on the speed, this function classifies the vehicle as an overspeed vehicle. The term "this" refers to the current document that requires map reduction. var avgspeed_reducemap = function(key, speed) {       var total =0;       for (var i = 0; i 
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Implementing MongoDb Map Reduce using Aggregation

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