mouse wheel zoom image js

<script type="text/javascript">
(function(){
 
var zooming=function(e){
    e=window.event ||e;
    var o=this,data=e.wheelDelta || -e.detail*40,zoom,size; 
    if(!+'\v1'){//IE
        zoom = parseInt(o.style.zoom) || 100; 
        zoom += data / 12;
        if(zoom > zooming.min) 
            o.style.zoom = zoom + '%';
        e.returnValue=false;
    }else {
        size=o.getAttribute("_zoomsize").split(",");
        zoom=parseInt(o.getAttribute("_zoom")) ||100;
        zoom+=data/12;
        if(zoom>zooming.min){
            o.setAttribute("_zoom",zoom);
            o.style.width=size[0]*zoom/100+"px";
            o.style.height=size[1]*zoom/100+"px";
        }
        e.preventDefault(); 
        e.stopPropagation();//for firefox3.6
    }
};
zooming.add=function(obj,min){// first parameter is for the image need to zoom ,min define the image zoom size ,default to 50
    zooming.min=min || 50;
    obj.onmousewheel=zooming;
    if(/Firefox/.test(navigator.userAgent))//if Firefox
        obj.addEventListener("DOMMouseScroll",zooming,false);
    if(-[1,]){//if not IE
        obj.setAttribute("_zoomsize",obj.offsetWidth+","+obj.offsetHeight);
    }
};
 
window.onload=function(){//must be onload , in order to get the image size
    zooming.add(document.getElementById("test"));
}
})()
</script>

 <img alt='' id='test' src="../demo/pflimg/bcms.gif" />