js 更改img图片
<img id="myimg" src="http://bbs.blueidea.com/images/default/logo.gif">
<script>
function cha(imgId){
document.getElementById(imgId).src = "http://bbs.blueidea.com/images/default/jinjin_4409.gif";
}
setTimeout (function(){cha("myimg")},1000)
</script>
