javascript 通过模块模式实现代码访问控制

<script type="text/javascript">
    // 在匿名函数中使用var关键字
    (function(){
        var privateField = 42;
        function innerFunc(){
            notSoPrivate =43;
            return notSoPrivate;
        }
        alert(privateField); // 42
        privateField = innerFunc(); // 
        alert(notSoPrivate); // 43

    })();
    alert(typeof privateField); // undefined
    alert(notSoPrivate);        // 43 变量泄露
</script>

var obj =(function (){
    var privateField = 42;
    var publicField = "foobar";
    function processInternals(){
         alert(‘Internal stuff : ‘ + privateField);
    }
    function run(){
        processInternals();
        alert(‘still private stuff : ‘ + privateField);
        alert(‘Public stuff : ‘ + publicField);
    }
    return {
        publicField : publicField,
        run : run
    };
})();
obj.run(); // 弹出 internal， still private， pupublic
alert(obj.publicField); // foobar
alert(obj.processInternals()); // Undefined
alert(obj.privateField); // undefined