js绑定带参数的事件以及手动触发事件

1. html部分

<div>
    <div id="tab">
        <h2>标题一</h2>
        <h2>标题二</h2>
        <h2>标题三</h2>
        <h2>标题四</h2>
    </div>
    <dl id="tabcon">
        <dd>内容一</dd>
        <dd>内容二</dd>
        <dd>内容三</dd>
        <dd>内容四</dd>
    </dl>
</div>

2. js部分

<script type="text/javascript" defer="defer">
var tab = document.getElementById("tab").getElementsByTagName("h2");
function swap(n) {
    returnfunction() {
        for(var i=0; i<tab.length; i++) {
            document.getElementById("tabcon"+ i).style.display ="none";
            document.getElementById("tab"+ i).className ="";
        }
        document.getElementById("tabcon"+ n).style.display ="block";
        document.getElementById("tab"+ n).className ="focus";
    }
}
for(var i=0; i<tab.length; i++) {
    tab[i].setAttribute("id", "tab"+ i);
    if(window.addEventListener) {
        tab[i].addEventListener("mouseover", swap(i), false);
    } elseif(window.attachEvent) {
        tab[i].attachEvent("onmouseover", swap(i));
    }
}
var tabcon = document.getElementById("tabcon").getElementsByTagName("dd");
for(i=0; i<tabcon.length; i++) {
    tabcon[i].setAttribute("id", "tabcon"+ i);
}
if(document.createEvent) {
    var evObj = document.createEvent('MouseEvents');
    evObj.initEvent( 'mouseover', true, false);
    tab[0].dispatchEvent(evObj);
} elseif( document.createEventObject) {
    tab[0].fireEvent('onmouseover');
}
</script>

html代码与js分离，不干扰搜索引擎抓取
兼容IE和Fx，其中没有on的事件是火狐下的写法