lovecoding
/
W250511


			
							123456789101112131415161718192021222324252627282930313233343536373839404142
							<!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>
        // 对象中的属性不允许重复  但是symbol类型的属性可以重复
        let obj = {
            userName:"张三",
            age:18,
            sex:"男"
        }

        
        console.log(obj[Symbol("a")]);
        obj.age = 20;
        obj.age = 30;
        // symbol  
        // 可以通过Symbol类型的属性名 来访问属性值
        // symbol 一般用作于受保护的属性
        let a = Symbol();
        let b = Symbol();
        obj[b] = "world";
        obj[a] = "hello";
        console.log(obj);
        console.log(obj[a]);
        console.log(obj[b]);

        // 遍历对象中的属性 Symbol类型不能被遍历
        for(let key in obj){
            console.log(key);
        }


    </script>
</body>
</html>