<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body {
            font-family: "Microsoft YaHei", serif;
        }

        body, dl, dd, p, h1, h2, h3, h4, h5, h6 {
            margin: 0;
        }

        ol, ul, li {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        img {
            border: none
        }
    </style>
</head>
<body>

<script>

    // 遍历数组，可以返回一个数组

    // 这个和6是一样的
    // 就是多一个返回值

    let a = [1,2,4];

    let b = a.map(function (x,y,z) {
        console.log(x, y, z);
        return x*x
    });

    console.log(a);
    console.log(b);


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