js 兼容设置透明度

function setAlphaOpacity(elm,value){
	elm=typeof elm=="string"?document.getElementById(elm):elm;
	if(document.all){  //IE
		elm.style.filter='alpha(opacity='+value+')';
	}else{             //FF
		elm.style.opacity=value/100;
	}
}
function setAlphaOpacity(elm,value){
	elm=t