节选代码
function showPic(whichpic){
var source=whichpic.getAttribute("href");
var placeholder=document.getElementById("placeholder");
placeholder.setAttribute("src",source);
var text=whichpic.getAttribute("title");
var description=document.getElementById("description");
description.childNodes[0].nodeValue=text;
return false;}
<a href="images/firework.jpg" onclick="return showPic(this); " title="A fireworks display">Firework</a>
除了ie9firefox，safari等都ok啊
------解决方案--------------------
最好
description.innerHTML = text;
description.childNodes[0].存在吗