js作用域闭包

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="dd"></div>
</body>
    <script>
        function f1() {

            var city = "上海";

            function f() {
            var dd = document.getElementById("dd");
            dd.innerHTML=city;  /*上海*/
            }
            return f; /*把f函数的值返回给f1*/
        }
        var ret = f1();
        ret(); /*运行ret*/

    </script>
</html>
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原文地址：https://www.cnblogs.com/TKOPython/p/12846122.html