????????????????????????????????????????????????閉包做私有變量計數器
閉包的用途：私有變量計數
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<script type="text/javascript">
//閉包的用途：私有變量計數器
var count = (function(){
var a = 0;
function bb(){
a++;
return a;
}
return bb;
})();
//每調用一次count当船，a就自增一次
alert(count());//1
alert(count());//2
var c = count();
alert(c);//3
</script>
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? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 閉包做選項卡
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>閉包做選項卡</title>
<style type="text/css">
.btns{
width: 500px;
height: 50px;
}
/*選項卡的樣式*/
.btns input{
width: 100px;
height: 50px;
background-color: #ddd;/*默認灰色*/
color: #666;
border: 0px;
}
/*被選中的選項卡的樣式*/
.btns input.cur{
background-color: gold;
}
/*內容區(qū)的樣式*/
.contents div{
width: 500px;
height: 300px;
background-color: gold;
display: none;/*默認隱藏*/
line-height: 300px;
text-align: center;
}
/*被選中的內容區(qū)的樣式*/
.contents div.active{
display: block;
}
</style>
<script type="text/javascript">
//閉包做選項卡
window.onload = function(){
var aBtn = document.getElementById('btns').getElementsByTagName('input');
var aCon = document.getElementById('contents').getElementsByTagName('div');
// alert(aCon.length);
//循環(huán)所有的選項卡按鈕
for(var i=0; i<aBtn.length; i++){
(function(i){
//給每個選項卡按鈕添加點擊事件
aBtn[i].onclick = function(){
//遍歷所有選項卡按鈕
for(var j=0; j<aBtn.length; j++){
//將每個選項卡按鈕都設為灰色
aBtn[j].className = '';
//將每個內容區(qū)都隱藏
aCon[j].className = '';
}
//this代表當前點擊的Button對象
this.className = 'cur';//當前點擊的按鈕為金色
// alert(i);//不加閉包時羽戒，不管點哪個按鈕通危，i都等于3
//加閉包保存了索引值才有效
aCon[i].className = 'active';//當前點擊的按鈕對應的內容顯示
}
})(i);
}
}
</script>
</head>
<body>
<div class="btns" id="btns">
<input type="button" value="tab01" class="cur">
<input type="button" value="tab02">
<input type="button" value="tab03">
</div>
<div class="contents" id="contents">
<div class="active">tab文字內容一</div>
<div>tab文字內容二</div>
<div>tab文字內容三</div>
</div>
</body>
</html>
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????????????????????????????????????????????????????跳轉的源頁面
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>跳轉的源頁面</title>
<script type="text/javascript">
<!--
存儲跳轉的源頁面
? -->
? var backUrl = document.referrer;
</script>
</head>
<body>
<a >北財網</a>
</body>
</html>
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