Install And Setup React App on Ubuntu
2K- by KnowledgeHut
- 18th Jan, 2021
- Last updated on 11th Mar, 2021
- 7 mins read
React is a JavaScript library for building user interfaces. It is opensource and maintained by Facebook.
You can read more about React here.
In this blog we are going to learn how to install and setup a React App on Ubuntu (version 16 and above).
Prerequisites
This blog assumes that you are using Ubuntu 16 or above versions and you have all the privileges to install the software in the machine, and also have access to the required websites mentioned in the blog.
System Requirements:
- Ubuntu 16 or above
- Minimum 4GB RAM
- Visual Studio Code installed.
Why should we choose React, and what are its advantages?
- React is built on JavaScript which makes it easier to learn and easier to use.
- React is component based which means we can write re-usable components. Start with small things, which you use to build bigger things, which you use to build apps.
- React is lightweight compared to Angular; which in turn makes your application faster to load—which is very important from the user’s point of view.
- React ensures faster rendering of DOM (document object model), this has been achieved by the introduction of Virtual DOM-currently, one of the benefits of using React for heavy loaded and dynamic software solutions.
- React has a helpful and interactive developer toolset which makes it easy to debug. React Developer Tools is a browser extension available for both Chrome and Firefox. It enables developers to observe reactive component hierarchies, discover child and parent components, and inspect their current state and props.
- React uses JSX(JavaScript XML) which has HTML-like syntax, making it easy to code and understand.
- React has strong community support on Github, Stackoverflow and many other platforms.
- React is SEO friendly.
There are certainly many other nice features about using React.
What is Node.js?
Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js is an Open Source Server Environment that is free and runs on almost all Operating Systems (Windows, Linux, Unix, Mac OS X, etc.).
You can read more about Nodejs here.
Why do we need Nodejs for React apps?
Node.js lets developers use JavaScript to develop variety of applications like network applications, command line tools, web APIs, mobile applications, web applications etc.
React usually runs on Node Server in development, but we can make use of other Servers likes Apache or Nginix to run React App in production. You do not need NodeJS to run React in production.
What is NPM, why do we need NPM for React apps?
NPM (Node Package Manager) is a dependency management tool for JavaScript applications. It is Open Source and also has command line utility for interacting with the application that aids in package installation, version management, and dependency management.
React does not ship with all the features by itself, so it uses external packages to add the required features to the React application. These packages are maintained by NPM (Node package manager) which is shipped with Nodejs in development.
You can read more about npm here.
We can use yarn instead of NPM during development and production for React apps.
Install Node.js
There are many ways to install Node.js in an Ubuntu machine.
- Install Node.js from the Ubuntu repository
- Install Using a PPA (personal package archive)
Using the first method we will not get the latest version of Node.js installed so we will choose the second method where we will get the latest version of Node.js installed.
Installing Using a PPA (personal package archive)
To get the latest version of Node.js installed on ubuntu, add a PPA (personal package archive). It is maintained by NodeSource.
Open terminal and run below commands:
- Install curl: Run below command on terminal
Command: sudo apt-get install curl
- Set the NodeSource PPA: Run below command on terminal
Command: curl -sL https://deb.nodesource.com/setup_current.x | sudo -E bash –
The PPA will be added to your configuration and your local package cache will be updated automatically.
You can read more about available versions of Node.js in nodesource here.
- Install Node.js: Run the below command on terminal
Command: sudo apt-get install -y nodejs
- Check for Node.js Installation: Run below command on terminal
Command: node -v
It has to show the version of node installed in this case v15.4.0
Now let's see how we can install and setup React app in Ubuntu machine
- Using create-react-app (installing create-react-app using npm)
- Using npx (Recommended in React docs)
Using create-react-app (npm)
In setting up a React project we come across tools like babel and webpack which are not easy to understand and configure for a person who is new to React and JavaScript. There are several tools that help to sort this problem. One of them is create-react-app. This is the easiest to setup. Create-react-app comes with production grade configurations pre-built. You can alter the configurations by ejecting from the create-react-app as well.
Follow the below steps to install using npm create-react-app
- Go into your desired location where you want to start your react app using ‘cd’ command
- Run below command to install create-react-app using npm
Command: npm install -g create-react-app
- Now Run create-react-app on terminal to setup a React-app.
Command: create-react-app hello-world
- This creates a folder with the name hello-world. You can navigate into the folder using ‘cd’ command and look at the project structure.
This gives the React app which we can use, but React recommends using npx.
Using npx command:
npx is the package runner, since npm version 5.2.0 npx is pre-bundled with npm.
Read more about differences npx and npm here.
Follow the below steps to setup using npx.
- Go into your desired location where you want to start your react app using ‘cd’ command
- Run the below command to setup React app using npx
Command: npx create-react-app my-app
That’s it! Your React app is ready with a single command.
- This creates a folder with the name hello-world. You can navigate into the folder using ‘cd’ command.
- Now open the project in vs-code
When you open the project in visual studio code the structure looks like this.
Now let's have a look at the files and folders we have:
- node_modules: This folder is managed by package manager (npm) and contains all the project library dependencies. We should not edit any file inside this folder.
- public: This folder contains the assets that should be served publicly without any restrictions and contains files like index.html, favicon, manifest.json
- src: This is the folder that contains all the files that are used to create web applications. As a react developer you are likely to spend a lot of time in this folder creating components and other sources of code.
- .gitignore: This file has all the assets which should be ignored by git while we publish our code to GitHub eg: node_modules
- package.json: This is a JSON file which has all information about the app such as name, dependencies, scripts we use to run the application etc.
- Readme.md: This is a markdown file where you specify the things which you want to show when someone visits your project on GitHub.
Now let's run our first React app!
- Open the terminal integrated with Visual studio code or just stay in the ubuntu terminal; either is fine. Let's use the integrated terminal.
- Run the app using the following command:
Command: npm start
This opens the app in your favourite browser as shown below:
Now, let's make our first code changes:
On navigating to src folder, you will find App.js file, through which the whole app is run inside the browser. Change the code as you see below and save by hitting ctrl+s.
Now look at the browser where the app is running. It looks like the one in the image below.
Congratulations on making your first React app!
What you have learnt:
- What is React and why it should be used
- What is Node.js, and how it should be installed on Ubuntu.
- What is npm
- What is create-react-app
- How to setup React-app on Ubuntu
- How to run the React-app
- How to make code changes to create your first React application.
React has rapid changes for every new version. It is important to keep yourself updated with the latest releases of React, so that you can make your life as a React developer easier!
KnowledgeHut
KnowledgeHut is an outcome-focused global ed-tech company. We help organizations and professionals unlock excellence through skills development. We offer training solutions under the people and process, data science, full-stack development, cybersecurity, future technologies and digital transformation verticals.
Website : https://www.knowledgehut.com
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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. 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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. 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- 13 May 2021
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Popular among both enterprises and startups, Mong... Read More
How to Work With Forms In JavaScript
By KnowledgeHut
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.
1681
- by KnowledgeHut
- 09 Jun 2021
- 8 mins read
Forms also referred as web forms are a very import... Read More
Introduction to Web APIs in JavaScript
By Dheeraj Kumar
Before we talk about APIs in JavaScript and how to use them, we need to know what exactly we mean by APIs. API stands for Application Programming Interface and is a concept that is not limited or specific to JavaScript, but is used in almost all web application languages. Being a web developer, it is expected that you know about API, so let’s try to understand the concept first. As a concept, API has been there since more than 50 years, but in recent years it has become very popular and has outlined a different method for how we create our applications. Now imagine you are creating a web application where users can sign up and talk about their recent travels, write stories, post pictures and share them. As an add-on they should be able to share the same across multiple platforms like Facebook, Instagram etc. How do we do that? We don’t have access to the Instagram application or their data. We don’t know how they are managing their data and whether data from our application will fit into their databases. Let’s try to imagine how Instagram would allow add-on without APIs. Perhaps we might drop an email to Instagram asking them to allow us access to their databases where we can write content. They may have received millions of other such requests from people who also need to use Instagram add-ons. Instagram will go through our requests and the million others and probably would use a lucky draw to decide who gets access to their databases. This is obviously not a reasonable solution and without any reasonable solution all applications in the world will just become isolated; which means they can’t communicate and can’t support each other’s features. Luckily our imagination is just that!Fortunately, we are living in a world with APIs around us which allow us to easily communicate with other apps. I can create an application where I can use Google’s search, Facebook’s feed, Instagram’s post, twitter’s tweets all in one app. This is all possible using API. As the name suggests, it allows us to open an interface which can then be used by other apps to communicate using the interface. How does an API work?The purpose of API is to communicate between apps with each other as intermediary, where both apps might have been built with different tools and technologies. It can be achieved by using api standards like REST, SOAP which outline protocols or sets of rules which the client (who needs to call) and server (who serves client’s requests) need to follow. These standards are key to communication. These standards outline what a request should look like and the format in which client should expect response from server. Every api exposes its endpoints (also called entrypoints), which allows its client to use it to access features of apis. For example, in JavaScript, to work with DOM, it exposes Document as an entrypoint in order to work with multiple methods. It allows its client to use it in order to manipulate DOM. In JavaScript however we use containers, which are nothing but HTML controls which can call APIs and response can be rendered within that control. JavaScript: An Introduction JavaScript is one of the most widely used programming languages, even though it is mainly used on browsers to render HTML and CSS. It can also run on our servers to handle client requests, connect with databases and do almost everything any other programming language does on the server. This makes it a significant tool that needs to be learned. Here, we are going to discuss about APIs which are provided by JavaScript to work with almost every aspect of a web application. APIs in JavaScript JavaScript, being a very widely used programming language has a very large set of APIs available, which make a JavaScript developer’s life a lot easier. JavaScript is also a multi-purpose language which means it can not only work on browsers, but also on servers or phones. To support different platforms, it has a different set of APIs to work with. It also provides a rich set of controls and other features like storage on client which are all easily availed by JavaScript. Browser APIs in JavaScript Browsers use JavaScript to display web pages, handle user interactions, send requests to servers and to receive responses. To make all this possible, JavaScript provides browser APIs which can be used to perform browser related functions: Working with DOM DOM stands for Document Object Model, which is a structure that holds all HTML controls on a web page. It not only holds but also allows us to add remove controls from it. You might have worked with document API which is used to get, push or even remove elements from DOM, all of this is coming from JavaScript DOM API. Example: document.getElementById(“header”).text(“This is a header”); Request data from server JavaScript is widely used to optimize web pages by updating only a part of a webpage instead of loading the entire page. for example, when you like a post on Facebook, it doesn’t load the entire page again, it only updates that particular post. Similarly, when we tweet on Twitter it doesn’t reload the entire page to show new tweets. This is how JavaScript makes partial calls to the server using popular fetch, AJAX apis. Example: const response= await fetch(url); // when response is success which is status 200 if (response.ok) { // receive response from server. let json = await response.json(); } else { // if there are errors returned by server, show the error alert("Error occured" + response.status); }Store data at client Even though we have our databases working smoothly on servers processing terabytes of data every day, you might still want to store a chunk of data on the client’s browsers to optimize the application performances. How do we do that? Again JavaScript will show us the way, by providing APIs like localStorage, sessionStorage which we can use to store data on client’s browser and remove it whenever we want. The difference between localStorage and sessionStorgae is that data which we store in localStorage persists even after closing the browser or tab, whereas data stored in sessionStorage gets cleared as soon as the tab or browser is closed. Now both of these have its own advantages depending on your requirement.sessionStorage.setItem('key', value); sessionStorage.getItem('key') localStorage.setItem('key', value); sessionStorage.getItem('key';)Work with Graphics There are lot of popular applications where you might have seen 2D or 3D graphics created using user’s interaction allowing users to create such drawings, and I am not talking about just CSS (Cascaded Style Sheets). Yes, CSS has its role to play, but to allow users to create 2D/3D drawings on the web we need more than just CSS. JavaScript provides canvas api which can be used to work with pixels on web page to draw 2D/ 3D images which will be within html tag.Third Party APIs. Integration with other applications, the structures of which we don’t have much information about, can be difficult. But JavaScript allows us to integrate with many popular third-party apps like Twitter, YouTube, Facebook. For example, you have your company’s website where you also want to display recent tweets that your company’s Twitter account has tweeted. How do we do that? JavaScript’s Twitter API is the answer. This is not only for Twitter, but a lot of other popular apps can be integrated into your own web page using JavaScript’s third party APIs. Web Audio API Audio API in JavaScript provides a smooth implementation of audio controls over a webpage. This includes multiple play controls on audio, and audio effects on the web. Web Audio API has multiple interfaces which include operations related to visualization effects, audio destinations, merging audio channels and audio processing. Example Play Geolocation APIThere are many web apps which work best with information of user’s locations, for example, if you are looking for restaurants nearby, you will get better results if Google knows your location. It is obviously up to the user’s consent if they want to share their location or not due to privacy concerns, but if they do want to share, geolocation API provides location of users to web applications. Example: var address = document.getElementById("address"); function accessUserLocation() { if (navigator.geolocation) { navigator.geolocation.getCurrentPosition(displayLocation); } } function displayLocation(location) { address.innerHTML = "Latitude: " + location.coords.latitude + "Longitude: " + location.coords.longitude; }History API History API is another useful although rarely used API, used if you want to allow user to traverse back and forth on a web application. History API runs with window objects using three different methods available-- go, back and forward. Example: // Visit page visited previously window.history.back(); // Traverse to forward on web page. window.history.forward(); // Move forward by 1 page window.history.go(1); Web Workers API Workers can be created using constructors in JavaScript, which can run a JavaScript file under worker thread context, which is different from the context of windows in JavaScript. There are a few exceptions on what kind of code we can run under worker thread, for example we can’t manipulate DOM using worker thread. With this a question arises-- if worker thread is different form main window thread, then how do they communicate? Because even though it is running in a different thread, the worker can still execute many window methods. To make this possible, the worker and main thread communicate using postMessage() method; to send data whenever onmessage event is called and handled. Example: const worker = new Worker('input.js'); Here input file which is a JavaScript file will contain the code which you need the worker thread to execute. Most Popular JavaScript APIs Browser APIs – We have discussed them in detail and since JavaScript leads how web applications are rendered on browser, the popularity of browser APIs is obvious. Canvas APIs – This is another favorite API of many developers who work in the graphics domain and need interactive applications for their client to easily work with drawings and graphics on web pages. SocialMedia APIs – This is very common nowadays. Any web application that targets an audience, needs social media integrations in their app, such as Facebook, Twitter, Instagram APIs, where they can showcase recent activities on their web page. Storage APIs – Every site I browse now a days pops up a panel asking me to accept cookies settings. Why? Because it helps the applications work well with user’s interaction and responses to the app, and the storage is not limited to cookies. sessionStorage and localStorage are widely used in JavaScript applications to store user’s info on client’s browsers. We just can’t imagine a life without storage APIs in JavaScript! JavaScript tools and relationship between themJavaScript Libraries There are JavaScript libraries like jQuery and React which implement JavaScript with their own new syntax. For example, the way we access our DOM using vanilla JavaScript and the way jQuery does it is different, but in the end, both use the same API which we have discussed above. Another example is when using React, where it extends JavaScript with JSX to embed JavaScript with HTML in React components.JavaScript FrameworksJavaScript Frameworks like Angular and Vue make most of the JavaScript APIs as they are built on top of JavaScript. The difference between the frameworks is in the structure, data flow and different patterns which they use to make it easier to work with JavaScript and implement its APIs. For example, Angular uses Dependency Injection to inject services into the component’s constructors, making it a sophisticated form of implementing inversion control which would be not this smooth with vanilla JavaScript. Frameworks like Angular try to prevent users from manipulating DOM directly as it is an expensive operation. However, it doesn’t mean it doesn’t update DOM at all. In the end, Angular uses DOM manipulation internally in quite an effective way, using the same APIs we have discussed above.Conclusion An API can be compared to a phone with unlimited talk time that is given to an application, allowing it to communicate with all other applications in the world. Why do we need this? Because one application doesn’t need to and can’t do everything. They need each other’s help. APIs can be for external as well internal use. External APIs allows an app to communicate with other apps, and internal or built-in APIs allow developers to work effectively with the tools. JavaScript being the most popular language in the world is aware of this and hence presents plenty of interfaces for us as developers to use in our applications. Be it working with storage, creating controls, integrating with Twitter, presenting media, or drawing graphics, JavaScript will not let you down.
7321
- by Dheeraj Kumar
- 09 Jun 2021
- 11 mins read
Before we talk about APIs in JavaScript and how to... Read More
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