javascript onclick，匿名函数

javascript onclick, anonymous function

我是一个初级的javascript程序员。我正在尝试创建类似于lightbox 2的东西，但要简单得多。我想自己白手起家的唯一原因是为了学习。然而，我一直停留在最后一个关键的部分，它显示图像。我认为问题在于我试图使用onclick来分配匿名函数：elem[i].onclick=function()litebox focus(imgsource，imgtitle)；return false；. 如果你运行我的代码并尝试点击谷歌的标志，它会显示雅虎的标志和标题，而不是谷歌的标志和标题。但是，当你点击雅虎的标志时，它会很好地工作，所以匿名函数似乎只适用于最后一个循环。事先谢谢！！！！

为了您的方便，我将整个CSS/JS/XHTML放在一个页面中。

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<html>
<head>
Erik's Script

<style type="text/css">
#liteBoxBg, #liteBox {
display: none;
}

#liteBoxBg {
background-color: #000000;
height: 100%;
width:100%;
margin:0px;
position: fixed;
left:0px;
top: 0px;
filter:alpha(opacity=80);
-moz-opacity:0.8;
-khtml-opacity: 0.8;
opacity: 0.8;
z-index: 40;
}

#liteBox {
background-color:#fff;
padding: 10px;
position:absolute;
top:10%;
border: 1px solid #ccc;
width:auto;
text-align:center;
z-index: 50;
}
</style>

<script type="text/javascript">

window.onload = start;

function start(){

var imgTitle ="No title";
var imgSource;
var elem = document.getElementsByTagName("a");
var i;

//Dynamically insert the DIV's to produce effect
var newDiv = document.createElement('div');
newDiv.setAttribute("id","liteBox");
document.getElementsByTagName("body")[0].appendChild(newDiv);

newDiv = document.createElement('div');
newDiv.setAttribute("id","liteBoxBg");
document.getElementsByTagName("body")[0].appendChild(newDiv);

//Check those anchors with rel=litebox
for(i = 0;i < elem.length;i++){
if(elem[i].rel =="litebox"){
imgSource = elem[i].href.toString();
imgTitle = elem[i].title;
elem[i].childNodes[0].style.border="0px solid #fff";
elem[i].onclick = function (){liteBoxFocus(imgSource,imgTitle); return false;};
}
}

//When foreground is clicked, close lite box
document.getElementById("liteBoxBg").onclick = liteBoxClose;
}

//Brings up the image with focus
function liteBoxFocus(source,title){
document.getElementById("liteBox").style.display ="block";
document.getElementById("liteBox").innerHTML ="" + title +"" +
"<img src='" + source +"'/><br />" +
"<img src='images/litebox_close.gif' border='0' alt='close'/>";
document.getElementById("liteBoxBg").style.display ="block";
}

//closes lite box
function liteBoxClose(){
document.getElementById("liteBox").style.display ="none";
document.getElementById("liteBoxBg").style.display ="none";
return false;
}

</head>

<body>

<img src="http://www.google.com/intl/en_ALL/images/logo.gif" alt="" />

<a href="
http://www.barbariangroup.com/assets/users/bruce/images/0000/4121/yahoo_logo.jpg" rel="litebox" title="Yahooo Logo"><img src="
http://www.barbariangroup.com/assets/users/bruce/images/0000/4121/yahoo_logo.jpg" alt="" />

</body>
</html>

事件处理程序形成一个闭包，它记住一个指向封闭范围中变量的"活动"指针。因此，在实际执行时，它们具有imgSource和imgTitle的最后一个值。

相反，您可以使用此模式来本地化变量值。每次调用getclickhandler时，它都会在getclickhandler中创建源代码和标题的副本。因此，返回的函数会记住循环迭代中的值。

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//Check those anchors with rel=litebox
for(i = 0;i < elem.length;i++){
if(elem[i].rel =="litebox"){
imgSource = elem[i].href.toString();
imgTitle = elem[i].title;
elem[i].childNodes[0].style.border="0px solid #fff";
elem[i].onclick = getClickHandler(imgSource, imgTitle);
}
}

//Brings up the image with focus
function getClickHandler(source,title){
return function() {
document.getElementById("liteBox").style.display ="block";
document.getElementById("liteBox").innerHTML ="" + title +"" +
"<img src='" + source +"'/><br />" +
"<img src='images/litebox_close.gif' border='0' alt='close'/>";
document.getElementById("liteBoxBg").style.display ="block";
}
}