代码如下:
<a href="#button" onMouseOver="fnChange()"><img name="Image50" border="0" src="../media/sys_b_diary.gif" width="74" height="36">.......
function fnChange()
{
    document.all.Image50.src = "../media/sys_b_diary_on.gif";
}

解决方案 »

  1.   

    首先,你要创建两个image对象,将两张图片一次性下载到客户端,然后再在onMouseover和onMouseout更换img元素的src属性
      

  2.   

    <script language="JavaScript">
    <!--
                    function MM_swapImgRestore() { //v3.0
                      var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
                    }                function MM_preloadImages() { //v3.0
                      var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
                            var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
                            if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
                    }                function MM_findObj(n, d) { //v3.0
                      var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
                            d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
                      if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
                      for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document); return x;
                    }                function MM_swapImage() { //v3.0
                      var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
                       if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
                    }</script><body onLoad="MM_preloadImages('../media/sys_b_diary_on.gif'); ">
       <a href="#button" onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('Image50','','../media/sys_b_diary_on.gif',1)" 
    <img name="Image50" border="0" src="../media/sys_b_diary.gif" width="74" height="36"></a><br>
    </body>