<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