<SCRIPT language=javascript>
    function replaceImg(sourceUrl,imgUrl) {
  if(document.all.mainpic.src == sourceUrl){
   return;
     }
  var img = new Image();
        img.src = sourceUrl;
        if(img.width>280){
            img.height=img.height/(img.width/280);
            img.width=280;
        }
        var elem = document.getElementById("mainpic");
        elem.width = img.width;
        elem.height = img.height;
        elem.src = sourceUrl;
        document.getElementById("mainPicUrl").href = "" + imgUrl;
    }
</SCRIPT>
缩略图代码:
<img style=""CURSOR: hand"" onclick="javascript:replaceImg('01.gif','01.gif')" src="01.gif" onload="javascript:if(this.height>this.width){this.height=80}else{this.width=80}" border="1">
<img style=""CURSOR: hand"" onclick="javascript:replaceImg('02.gif','02.gif')" src="02.gif" onload="javascript:if(this.height>this.width){this.height=80}else{this.width=80}" border="1">
<img style=""CURSOR: hand"" onclick="javascript:replaceImg('03.gif','03.gif')" src="03.gif" onload="javascript:if(this.height>this.width){this.height=80}else{this.width=80}" border="1">
<img style=""CURSOR: hand"" onclick="javascript:replaceImg('04.gif','04.gif')" src="04.gif" onload="javascript:if(this.height>this.width){this.height=80}else{this.width=80}" border="1">


全图代码:
<A id="mainPicUrl" onfocus="this.blur()" href="01.gif" target="_blank"><img id="mainpic" style="cursor: hand" src="01.gif" onload="javascript:if(this.height>this.width){this.height=280}else{this.width=280}" border="1" style="border-style: solid; border-color: #000000; padding: 1"></A>



现在想用onfocus触发，怎么实现？[em10]