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html从零开始9：javaScript简介，语句、标识符，变量，JavaScript引入到文件【搬代码】

news 来源：原创 2025/5/1 10:51:29

javaScript简介

javaScript语句、标识符

变量

var num =10;
var就是固定声明,num就是变量名，10就是变量；

<!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></title>
</head>
<body>

    <script>
        var num = 10;
        console.log(num)
    </script>
</body>
</html>

JavaScript引入到文件

嵌入到html文件中

<body>

    <script>
        var num = 10;
        console.log(num)
    </script>
</body>

引入本地独立js文件中

<body>

    <script src="./hellojs.js"></script>
</body>

var age = 20;
console.log(age)

引入网络来源文件

<!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></title>
    /*引入外部文件*/
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
</head>
<body>

   
    
</body>
</html>