What is react? Introduction to the basic use of react (with examples)

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Release： 2018-09-11 10:47:14

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This article mainly talks about some basic knowledge about react, so that everyone can learn more about the basics of react. Let us read this article now

React Introduction Series 1 (First introduction to React)

1. Introduction to React

React is a JavaScript used to build user interfaces Library. React is mainly used to build UI, and many people think that React is the V (view) in MVC. React originated as an internal project at Facebook. React has high performance and the code logic is very simple.

2. Features of React

Declarative design −React adopts a declarative paradigm, which can easily describe applications.
Efficient −React minimizes interaction with the DOM by simulating the DOM.
Flexible −React works well with known libraries or frameworks.
JSX − JSX is an extension of JavaScript syntax. React development does not necessarily use JSX, but it is recommended.
Component − Building components through React makes it easier to reuse code and can be well applied in the development of large projects.
One-way response data flow − React implements one-way response data flow, thereby reducing duplicate code, which is why it is simpler than traditional data binding.

3. Basic usage introduction

基本模板<!DOCTYPE html>
   <html>
     <head>
       <script src="../build/react.js"></script>
       <script src="../build/react-dom.js"></script>
       <script src="../build/browser.min.js"></script>
     </head>
     <body>
       <p id="example"></p>
       <script type="text/babel">

       </script>
     </body>
   </html>
   模板中代码一共用了三个库： react.js 、react-dom.js 和 Browser.js
   需要注意的是，它们必须首先加载。
   1）react.js是React的核心库。
   2）react-dom.js是提供与DOM相关的功能。
   3）Browser.js的作用是将JSX语法转为JavaScript语法，这一步很消耗时间，实际上线时，应将它放到服务器完成。
   $ babel src --out-dir build
   这个命令可以将src子目录的js文件进行语法转换，转码后的文件全部放在build子目录。

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Note: The type attribute of the last script tag is text/babel. This is because React's unique JSX syntax is incompatible with JavaScript. Wherever JSX is used, type="text/babel" must be added. If you need to use JSX, the type attribute of the script tag needs to be set to text/babel. (If you want to see more, go to the PHP Chinese website React Reference Manual column to learn)

补充一点：
   使用JSX，可以极大的简化React元素的创建，JSX抽象化了React.createElement()函数的使用，其语法风
格类似于HTML语法风格.不过，使用React并非必须使用JSX，JSX只是一种直观的创建React nodes的方法，它是对
React.createElement（）方法的抽象，通过Babel，JSX语句也可以直接在浏览器中运行，Babel内嵌了对JSX的支持。
   在运行时引用babel.js虽然容易使用而且还很方便，不过并不是一种好的方案，因为需要转换，所以更加耗时，
这一缺点在产品阶段显得更加明显。Babel是React团队选择的在使用React过程中转换ES*和JSX为ES5语句的工具。实际
   Babel主要用途是一个JavaScript转换器，它可以转换各种ES*代码为浏览器可识别的ES代码。就目前来说，Babel主
要会转换ES6和ES7语句为ES5语句，转换JSX看起来倒像是其的一个附加功能。babel.js与browser.js的关系 babel的
浏览器版本为browser.js（未精简）和browser.min.js（已精简）。所以最后一个文件也可以引入babel.min.js。

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4. Use React through npm (use create-react-app to quickly build React development Environment)

create-react-app comes from Facebook. This command can quickly build a React development environment without configuration. The project automatically created by create-react-app is based on Webpack ES6.

执行以下命令创建项目(支持node.js和npm)：
$ npm install -g create-react-app$ create-react-app my-app$ cd my-app/$ npm start

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This article ends here (if you want to see more, go to the PHP Chinese website react User Manual column to learn). If you have any questions, you can leave a message below. .

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