React(1)

1. 更新create-react-app的新版本，找到项目中的package.json, "react-scripts": "4.0.3",将版本号改成最新版，之后运行 npm install

2. JSX: part of React allows you to write some HTML syntax in javaScript.当我们写HTML时候实际上是在写JSX，这些JSX需要import到React中才能工作。这就是为什么要有

   import React from 'react'

3. react img 标签必须闭合，否则报错；

4. return 只能返回一个数值；除非使用Fragment

5. 关于{}

The curly braces are a special syntax to let the JSX parser know that it needs to interpret the contents in between them as JavaScript instead of a string. This process is generally referred to as "interpolation".

You need {} when you want to use a JavaScript expression like a variable or a reference inside JSX.

6. Fragment blog.logrocket.com/rendering-c…

   解决了只能return一个的问题。

import React, {Fragment} from "react";

function FAQ() {
    return (
        <Fragment>
            <p>Q. What is React?</p>
            <p>A. A JavaScript library for building user interfaces</p>
            <p>Q. How do I render sibling elements?</p>
            <p>A. Use Fragments</p>
        </Fragment>
    );
}