演示常用函数类型、演示常用数据类型

<!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>0330作业</title>
</head>
<body>
    <script>
        // 1.命名函数
        function sub(v1, v2){
            return v1-v2;
        }
        console.log(sub(2,1));
        // 2.1匿名函数
        let subn = function(v1,v2){
            return v1-v2;
        }
        console.log(subn(4,2));
        // 2.2立即调用函数（）
        console.log(
            (function(){
                return "Hello World.";
            })()
        )
        // 3.箭头函数
        let subv =  (v1,v2)=>{
            return v1-v2;
        }
        console.log(subv(8,5));
        // 3.2 一个参数的箭头函数
        let say = name=>{
            return "Hello, "+name;
        }
        console.log(say("Dave"));
        // 3.3 没有参数的箭头函数
        let email = ()=>{
            return "1234@qq.com";
        }
        console.log(email());
        // 3.4 只有一条语句可以不用大括号(默认return)
        let phpClass = ()=>"Hello, php.cn";
        console.log(phpClass());
        // 数据类型
        // 1.原始类型:number string boolean undefined null
        console.log(typeof 100);
        console.log(typeof "Hello");
        console.log(typeof true);
        let abc;
        console.log(typeof abc);
        let bcd = null;
        console.log(typeof bcd);
        // 2.引用类型: array object function
        // 引用类型判断不能用typeof, Array.isArray()
        let arr = [1,2,3,4]
        console.log(arr);
        console.log(arr[0]);
        let obj = {
            id:"1",
            option:"2"
        }
        console.log(obj);
        console.log(obj.id);
        console.log(obj['id']);
        function getName(){
            return "Hello, Dave";
        }
        console.log(getName());
    </script>
</body>
</html>
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