(function () {
        var str = '歡迎訪問我的主頁';
        alert(str);
    })();

    /* !function () {
        var str = '歡迎訪問我的主頁';
        alert(str);
    }()*/
     ~function () {
        var str = '歡迎訪問我的主頁';
        alert(str);
    }()

封閉函數(shù)用 ! 或者 ~ 還有()()

閉包

function aa(b) {
        var a = 12;
        function bb() {
            alert(a);
            alert(b);
        }
        return bb;
    }
    var cc = aa(24);
   //封閉函數(shù)寫閉包 
   /*var cc =(function (b) {
         var a = 12;
        function bb() {
            alert(a);
            alert(b);
        }
        return bb;
   })(24);*/
    cc()

閉包的用途
1.存索引

li{
        height: 30px;
        background-color: gold;
        margin-bottom: 10px;
    }
</style>
<script type="text/javascript">
    window.onload = function () {
        var ali = document.getElementsByTagName('li');
        
        for(var i=0; i<ali.length; i++){
            (function (i) {
                ali[i].onclick = function () {
                    alert(i)
                }
            })(i)
        }
    }

2.私有計數(shù)器

var count = (function () {
        var a = 0;
        function bb() {
            a++;
            return a;
        }
        return bb;
    })();
    alert(count());
    alert(count());
    var c = count();
    alert(c);