React (software) — A Video Map Guide

Declarative React adheres to the declarative programming paradigm.: 76 Developers design views for each state of an application, and React updates and renders components when data changes. This is in contrast with imperative programming. Components React code is made of entities called components.: 10–12 These components are modular and can be reused.: 70 React applications typically consist of many layers of components. The components are rendered to a root element in the DOM using the React DOM library. When rendering a component, values are passed between components through props (short for "properties"). Values internal to a component are called its state. The two primary ways of declaring components in React are through function components and class components.: 118 : 10 Since React v16.8, using function components is the recommended way. Function components Function components, announced at React Conf 2018, and available since React v16.8, are declared with a function that accepts a single "props" argument and returns JSX. Function components can use internal state with the useState Hook. React Hooks On February 16, 2019, React 16.8 was released to the public, introducing React Hooks. Hooks are functions that let developers "hook into" React state and lifecycle features from function components. Notably, Hooks do not work inside classes — they let developers use more features of React without classes. React provides several built-in hooks such as useState,: 37 useContext,: 11 : 12 useReducer,: 92 : 65–66 use

React does not attempt to provide a complete application library. It is designed specifically for building user interfaces and therefore does not include many of the tools some developers might consider necessary to build an application. This allows the choice of whichever libraries the developer prefers to accomplish tasks such as performing network access or local data storage. Common patterns of usage have emerged as the library matures. Unidirectional data flow Unidirectional data flow To support React's concept of unidirectional data flow (which might be contrasted with AngularJS's bidirectional flow), the Flux architecture was developed as an alternative to the popular model–view–controller architecture. Flux features actions which are sent through a central dispatcher to a store, and changes to the store are propagated back to the view. When used with React, this propagation is accomplished through component properties. Since its conception, Flux has been superseded by libraries such as Redux and MobX. Flux can be considered a variant of the observer pattern. A React component under the Flux architecture should not directly modify any props passed to it, but should be passed callback functions that create actions which are sent by the dispatcher to modify the store. The action is an object whose responsibility is to describe what has taken place: for example, an action describing one user "following" another might contain a user id, a target user id, and the type USER_FOLLOWED_ANOTHER_USER. The stores, which can be thought of as models, can alter themselves in response to actions received from the dispatcher. This pattern is sometimes expressed as "properties flow down, actions flow up". Many implementations of Flux have been created since its inception, perhaps the most well-known being Redux, which features a single store, often called a sin

React was created by Jordan Walke, a software engineer at Facebook, Inc. (now Meta), who initially developed a prototype called "F-Bolt" before later renaming it to "FaxJS". This early version is documented in Jordan Walke's GitHub repository. Influences for the project included XHP, an HTML component library for PHP. React was first deployed on Facebook's News Feed in 2011 and subsequently integrated into Instagram in 2012. In May 2013, at JSConf US, the project was officially open-sourced, marking a significant turning point in its adoption and growth. React Native, which enables native Android, iOS, and UWP development with React, was announced at Facebook's React Conf in February 2015 and open-sourced in March 2015. On April 18, 2017, Facebook announced React Fiber, a new set of internal algorithms for rendering, as opposed to React's old rendering algorithm, Stack. React Fiber was to become the foundation of any future improvements and feature development of the React library.[needs update] The actual syntax for programming with React does not change; only the way that the syntax is executed has changed. React's old rendering system, Stack, was developed at a time when the focus of the system on dynamic change was not understood. Stack was slow to draw complex animation, for example, trying to accomplish all of it in one chunk. Fiber breaks down animation into segments that can be spread out over multiple frames. Likewise, the structure of a page can be broken into segments that may be maintained and updated separately. JavaScript functions and virtual DOM objects are called "fibers", and each can be operated and updated separately, allowing for smoother on-screen rendering. On September 26, 2017, React 16.0 was released to the public. React 16.0 introduced error boundaries, a new component type that catches JavaScript errors anywhere in

The initial public release of React in May 2013 used the Apache License 2.0. In October 2014, React 0.12.00 replaced this with the 3-clause BSD license and added a separate PATENTS text file that permits usage of any Facebook patents related to the software:The license granted hereunder will terminate, automatically and without notice, for anyone that makes any claim (including by filing any lawsuit, assertion or other action) alleging (a) direct, indirect, or contributory infringement or inducement to infringe any patent: (i) by Facebook or any of its subsidiaries or affiliates, whether or not such claim is related to the Software, (ii) by any party if such claim arises in whole or in part from any software, product or service of Facebook or any of its subsidiaries or affiliates, whether or not such claim is related to the Software, or (iii) by any party relating to the Software; or (b) that any right in any patent claim of Facebook is invalid or unenforceable.This unconventional clause caused some controversy and debate in the React user community, because it could be interpreted to empower Facebook to revoke the license in many scenarios, for example, if Facebook sues the licensee prompting them to take "other action" by publishing the action on a blog or elsewhere. Many expressed concerns that Facebook could unfairly exploit the termination clause or that integrating React into a product might complicate a startup company's future acquisition. Based on community feedback, Facebook updated the patent grant in April 2015 to be less ambiguous and more permissive: The license granted hereunder will terminate, automatically and without notice, if you (or any of your subsidiaries, corporate affiliates or agents) initiate directly or indirectly, or take a direct financial interest in, any Patent Assertion: (i) against Facebook or any of its subsidiaries or corporate affiliates, (ii) against any party if