前言

前面学习了js，引入方式使用的是<script s"XXX.js">，今天来学习引入文件的其他方式，使用ES6 模块化编程，学习组件化编程中的全局注册和局部注册的方法。

复习

回顾前面学习内容，用<script s"XXX.js">引入js文件

在html文件中引入js文件

<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=<device-width>, initial-scale=1.0"><title>Document</title>
</head><body><script src="learn.js"></script><script>console.log(this.content)learn()</script></body>

js文件

const content = "模块化";
const learner = "MRJJ_9";
function learn()
{console.log(`${learner}在学习${content}`);
}

ES6 模块化导出导入

先导出js文件

export const content = "模块化";
export const learner = "MRJJ_9";
export function learn()
{console.log(`${learner}在学习${content}`);
}

简单写法，也可以写成下面这样的

解构赋值

import * as mrjj from './learn.js'

重命名为mrjj

导入js文件

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><script type="module">import * as mrjj from './learn.js'import {content} from './learn.js'console.log(content);console.log(mrjj.learner);mrjj.learn()
</script>
</body>
</html>

export default

导出一个完整的对象 export default

只能有一个export

export default{content : "模块化",learner : "MRJJ_9",learn(){console.log(`${this.learner}在学习${this.content}`);}
}

import mrjj_lr from './learnDefault.js'

需要取别名才能导入

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body>
<script type="module">import mrjj_lr from './learnDefault.js'mrjj_lr.learn()</script>
</body>
</html>

但在浏览器中不能使用

全局注册

<body><div id="aside"></div><script type="module">import {createApp} from 'https://unpkg.com/vue@3/dist/vue.esm-browser.js'import Asider from './Asider.js'import Counter from './Counter.js'const asideApp=createApp(Asider);// 全局注册const asideVM=asideApp.component('Counter',Counter).mount("#aside");</script>
</body>