React.js Components basic1 Venturads.com смотреть онлайн

React.js Components basic1

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In computing, React (sometimes React.js or ReactJS) is a JavaScript library[2] for building user interfaces.

It is maintained by Facebook, Instagram and a community of individual developers and corporations.[3][4][5]

React can be used in the development of single-page applications and mobile applications. It aims primarily to provide speed, simplicity, and scalability. As a user interface library, React is often used in conjunction with other libraries such as Redux.

The following is a rudimentary example of React usage in HTML with JSX and JavaScript.

One-way data flow
Properties (commonly, props) are passed to a component from the parent component. Components receive props as a single set of immutable values[10] (a JavaScript object). Whenever any prop value changes, the component's render function is called allowing the component to display the change.

Virtual DOM
Another notable feature is the use of a "virtual Document Object Model", or "virtual DOM". React creates an in-memory data structure cache, computes the resulting differences, and then updates the browser's displayed DOM efficiently.[11] This allows the programmer to write code as if the entire page is rendered on each change, while the React libraries only render sub components that actually change.

JSX
JavaScript XML (JSX) is an extension to the JavaScript language syntax[12]. Similar in appearance to HTML, JSX provides a way to structure component rendering using syntax familiar to many (if not most) developers. React components are typically written using JSX, although they do not have to be (components may also be written in pure JavaScript). JSX is similar to another extension syntax created by Facebook for PHP, XHP.

An example of JSX code: