前端代码（一）

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script type="module" src="./math.js"></script>
    <script type="module" src="./util.js"></script>
</head>

<script type="module">
    import {hello, getMsg} from './util.js'
    window.changeDivContent = function() {
        var divElement = document.getElementById('content')
        console.log('js i am coming...')
        divElement.innerHTML = getMsg()
    }
</script>
<body>
    <h1>Demo</h1>
    <div id="content"></div>
    <button onclick="changeDivContent()">显示内容</button>
</body>
<script>

</script>
</html>

math.js

export function sum(a, b){
    return a+b
}

function hello(){
    return 'hello math'
}

util.js

import {sum} from './math.js'


export function hello() {
    return 'hello util'
}

export function getMsg() {
    let sum_result =  sum(1, 2)
    console.log('sum_result:' + sum_result)
    return sum_result
}