What Is React Js

Posted on  by admin
Original author(s)Jordan Walke
Developer(s)Meta and community
Initial releaseMay 29, 2013; 8 years ago[1]
Stable release
  • React is a Javascript library used for building fast and interactive user interfaces.
Written inJavaScript
PlatformWeb platform
TypeJavaScript library
LicenseMIT License

It is developed by Facebook in 2011. Today, React is very popular with 144k stars on Github. React is a Javascript library used for building fast and interactive user interfaces. React is used to build single-page applications or mobile applications. You can create complex user interfaces using small isolated pieces of code called components. Components are building blocks of a React App. A component represents a piece of User Interface like buttons, textbox, etc. It is a javascript function or class which accepts properties(props) and returns a react element that describes how a section of UI should appear.

React Component Properties

A Component is a javascript function or class which accepts properties(props) and returns a react element that describes how a section of UI should appear.

There are two types of "modal" data in React:. Props: Props are used to send data to the component, it is equivalent to the arguments of the javascript function.

Parent component can pass data to the child component using props.

JSX Compiler

JSX Expressions

State: State is a javascript object that is initialized and managed by the component. It is like a data store for the react component. When the state or props of a component change, react renders the component using new data(props and state).

Should I Learn React JS?

However, react does not work on the DOM directly. Instead, it creates a virtual DOM in the memory and compares it with the original DOM. If there is a difference, react updates the real DOM to sync with the virtual DOM. React updates only the part of DOM which is modified instead of rendering the whole page again. In the next article, we will discuss some of the core features of React JS.

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Consider subscribing to our newsletter or follow us on our social channels (twitter, Facebook, LinkedIn). React is the most popular JavaScript front-end framework in use today. It's used by both established companies and new startups.

React was released by Facebook in 2013, and they still use it today for many of their applications.

React is a JavaScript library for creating user interfaces. Here are three places you'll find it being used:. This is where React got its start and where you'll find it used most often. React is component-based. An example of a component could be a form or even just a form field or button on a website. In React, you build up complete applications using components like these by nesting them. Components in React can manage their own state and communicate that state to child components. By "state," we mean the data that populates the web application. An example would be a user profile form that holds the state of the user's data, including first name, last name, and other values. This form component would have nested field components that it passes its state to in order to populate them. Components in React are also reusable, which means you can use one button component for every button on your site. If you need the button to look different, you can simply change its style. React Native is a JavaScript framework that uses React. With React Native, developers can apply web-based React principles to creating mobile apps for Android and iOS. Here, React is used to connect the mobile user interface of the application to the phone's operating system. Developers can also use React with Electron, another JavaScript library, to create cross-platform desktop apps. Some apps you may know about that are built with Electron include Visual Studio Code, Slack, Skype, Discord, WhatsApp, and WordPress Desktop. Let's look at a React example so you have a better idea of how it works. A React web application runs on one web page. Here's an example of an HTML file used to run a React app:. Using script tags, we import the JavaScript libraries necessary for React to run. React and React DOM are the basic React libraries we need. Babel is a JavaScript library that compiles the JSX language that React uses into JavaScript the browser can understand. The div element that has the root id is where the whole React app will run. And the script tag below that is where all the React code will go, which we'll look at in more detail next. To use React, you need to create components that use JSX. Below is an example component:. The component above is a simple JavaScript function that accepts a parameter called props — a special keyword in React used to pass data between components. The function returns the value attribute of props wrapped with what looks like an HTML h1 tag. This isn't actual HTML, yet. It's called JSX, a React-specific syntax that allows HTML-like text to co-exist with JavaScript. Below, we have another component that uses our Heading component. In fact, it uses it three times to create headings with different values. Note that the props in React are passed to child components as attributes of the JSX. You'll also notice that the name of this component is App. This is because it's our complete application. Everything in React is a component, including the whole application. To render this app to the browser, we need one more piece of code. This code tells React to render the results in the HTML element that has the root id. React is often compared to another JavaScript framework called Angular, but there are a lot of differences between the two. Here's an overview of some of the main distinctions between the two frameworks:. Web development: Angular is a complete front-end framework for building web applications. It's based on the MVC (Model-View-Controller) pattern. React, on the other hand, is for creating user interfaces — or just the View part of this pattern. This means you'll need other libraries or more code to create complete web apps, but you'll also have greater customizability for your features and structure. Updates: Angular operates directly on a web page's DOM, so the entire page must be updated when a change is made to its data model. React updates the virtual DOM. These updates are quicker because they don't trigger changes in the page layout itself. Plus, once React updates the virtual DOM, it's then compared to the real DOM, and only those parts that differ are updated — allowing for faster rendering and performance. Data binding: Angular uses both one- and two-way data binding, while React only uses one-way. With Angular, changes in data can trigger changes in the view and vice versa. But, with React, data only flows in one direction — which makes debugging an app easier. So, now you know a little about React and why developers use it to build applications. If you're ready to learn more about React and start building front-end web applications, our Learn React course will teach you the framework's fundamentals and essential concepts. To apply these newly learned skills and build a complete front-end web app, check out Create a front-end app with React. React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. Declarative views make your code more predictable and easier to debug. Build encapsulated components that manage their own state, then compose them to make complex UIs. Since component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep state out of the DOM. We don’t make assumptions about the rest of your technology stack, so you can develop new features in React without rewriting existing code. React can also render on the server using Node and power mobile apps using React Native. React components implement a render() method that takes input data and returns what to display. This example uses an XML-like syntax called JSX. Input data that is passed into the component can be accessed by render() via this.props. JSX is optional and not required to use React. Try the Babel REPL to see the raw JavaScript code produced by the JSX compilation step. In addition to taking input data (accessed via this.props), a component can maintain internal state data (accessed via this.state). When a component’s state data changes, the rendered markup will be updated by re-invoking render(). Using props and state, we can put together a small Todo application. This example uses state to track the current list of items as well as the text that the user has entered. Although event handlers appear to be rendered inline, they will be collected and implemented using event delegation. React allows you to interface with other libraries and frameworks. This example uses remarkable, an external Markdown library, to convert the