js 另存图片

var n=0;
function saveImg(url)
{
n==0?new function(){frames("saveAsImg").location=url,n=1}:null;
document.all("saveAsImg").readyState!="complete"?setTimeout(saveImg,10):so();
function so()
{
frames("saveAsImg").document.execCommand("SaveAs"),n=0
};
}
<iframe id="saveAsImg" name="saveAsImg" style="display:none"></iframe>
<img onclick="saveImg(src)" src=".........."/>