2种形式都可以
第一种：
复制代码 代码如下:
<script>
function SaveAs5(imgURL)
{
var oPop = window.open(imgURL,"","width=1, height=1, top=5000, left=5000");
for(; oPop.document.readyState != "complete"; )
{
if (oPop.document.readyState == "complete")break;
}
oPop.document.execCommand("SaveAs");
oPop.close();
}
</script>
<img src="t_screenshot_17616.jpg" id="DemoImg" border="0" onclick="SaveAs5(this.src)">

第二种：
复制代码 代码如下:
<script>
function SaveAs5(imgURL)
{
var oPop = window.open(imgURL,"","width=1, height=1, top=5000, left=5000");
for(; oPop.document.readyState != "complete"; )
{
if (oPop.document.readyState == "complete")break;
}
oPop.document.execCommand("SaveAs");
oPop.close();
}
</script>
<img src="../t_screenshot_17616.jpg" id="DemoImg" border="0">
<a href="#" onclick="SaveAs5(document.getElementById('DemoImg').src)"> 点击这里下载图片 </a>