閉包
function aa(b){
var a = 12;
function bb(){
alert(a);
alert(b);
}
return bb;
}
var cc = aa(24);
閉包就是函數里面由函數,也可以交函數的嵌套
閉包的用途
1.存索引
li{
height:30px;
background-color :red;
margin-bottom:10px;
}
</style>
<script type="text/javascript">
window.onload = functin(){
var ali = document.getElementsByTagName("li");
for(var i=0; i<ali.length; i++){
(function (i)){
ali[i].onclick = function(){
alert(i)
}
})(i)
}
}
2.私有計數器
var count = (function () {
var a = 0;
function bb() {
a++;
return a;
}
return bb;
})();
alert(count());
alert(count());
var c = count();
alert(c);
