大量Firefox和IE不兼容的javascript代码: runtimeStyle, event.srcElement

编写EasyCluster 1.6的mainleft的时候，遭遇了大量Firefox和IE不一样的js代码，如runtimeStyle, event.srcElement, parentElement, attachEvent。这些都是IE中管用的，在Firefox中要换成style, event.target, parentNode, addEventListener。Firefox中runtimeStyle和parentElement是没有的，而IE中style, runtimeStyle, parentElement, parentNode都是有的。

具体看下面的代码，下面的代码很简单，就是给所有的tr（除了id为roottr的）加上onmouseover, onmouseout事件（鼠标移入和移出的时候加背景和改变光标）：

     < script language = " javascript " >
     //  process tr backgrounds and cursor
     var  trarray, i, normalColor;
    trarray  =  document.getElementsByTagName( " tr " );
     <%
         //  firefox or IE?
        String useragent  =  request.getHeader( " user-agent " );
         if  (useragent.indexOf( " Firefox " )  ==   - 1 ) {
     %>
     for  (i = 0 ; i < trarray.length; i ++ ) {
         if  (trarray[i].id  !=   " roottr " ) {
            trarray[i].attachEvent( " onmouseover " , ProcessMouseOver);
            trarray[i].attachEvent( " onmouseout " , ProcessMouseOut);
        }
    }

     function  ProcessMouseOver(event)
    {
         if  (event.srcElement.tagName.toLowerCase()  ==   " td " ) {
            normalColor  =  event.srcElement.parentElement.style.backgroundColor; 
            event.srcElement.parentElement.runtimeStyle.backgroundColor   =   " #F7D12A " ;
            event.srcElement.parentElement.runtimeStyle.cursor  =   " pointer " ;
        }
         if  (event.srcElement.tagName.toLowerCase()  ==   " a "   ||  event.srcElement.tagName.toLowerCase()  ==   " img " ) {
            normalColor  =  event.srcElement.parentElement.parentElement.style.backgroundColor; 
            event.srcElement.parentElement.parentElement.runtimeStyle.backgroundColor   =   " #F7D12A " ;
            event.srcElement.parentElement.parentElement.runtimeStyle.cursor  =   " pointer " ;
        }

    }

     function  ProcessMouseOut(event)
    {
         if  (event.srcElement.tagName.toLowerCase()  ==   " td " ) {
            event.srcElement.parentElement.runtimeStyle.backgroundColor   =  normalColor;
            event.srcElement.parentElement.runtimeStyle.cursor  =   "" ;
        }
         if  (event.srcElement.tagName.toLowerCase()  ==   " a "   ||  event.srcElement.tagName.toLowerCase()  ==   " img " ) {
            event.srcElement.parentElement.parentElement.runtimeStyle.backgroundColor   =  normalColor;
            event.srcElement.parentElement.parentElement.runtimeStyle.cursor  =   "" ;
        }
    }
     <%
        }  else  {
     %>
     for  (i = 0 ; i < trarray.length; i ++ ) {
         if  (trarray[i].id  !=   " roottr " ) {
            trarray[i].addEventListener( " mouseover " , ProcessMouseOver,  false );
            trarray[i].addEventListener( " mouseout " , ProcessMouseOut,  false );
        }
    }

     function  ProcessMouseOver(event)
    {
         if  (event.target.tagName.toLowerCase()  ==   " td " ) {
            normalColor  =  event.target.parentNode.style.backgroundColor; 
            event.target.parentNode.style.backgroundColor   =   " #F7D12A " ;
            event.target.parentNode.style.cursor  =   " pointer " ;
        }
         if  (event.target.tagName.toLowerCase()  ==   " a "   ||  event.target.tagName.toLowerCase()  ==   " img " ) {
            normalColor  =  event.target.parentNode.parentNode.style.backgroundColor; 
            event.target.parentNode.parentNode.style.backgroundColor   =   " #F7D12A " ;
            event.target.parentNode.parentNode.style.cursor  =   " pointer " ;
        }

    }

     function  ProcessMouseOut(event)
    {
         if  (event.target.tagName.toLowerCase()  ==   " td " ) {
            event.target.parentNode.style.backgroundColor   =  normalColor;
            event.target.parentNode.style.cursor  =   "" ;
        }
         if  (event.target.tagName.toLowerCase()  ==   " a "   ||  event.target.tagName.toLowerCase()  ==   " img " ) {
            event.target.parentNode.parentNode.style.backgroundColor   =  normalColor;
            event.target.parentNode.parentNode.style.cursor  =   "" ;
        }
    }
     <%
        }
     %>
     < / script>