为什么这段ajax代码在IE上正常却在火狐下不行???
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>无标题文档</title></head><script type="text/javascript"> window.onerror=function(){ alert("error"); } window.onload=function(){ var odiv=document.getElementById("responsetext"); var XHR,str; str=(function(){ return "name=peter&age=18"; })(); if(window.ActiveXObject){ XHR=new ActiveXObject("Microsoft.XMLHTTP"); } else if(window.XMLHttpRequest) XHR=new XMLHttpRequest(); XHR.onreadystatechange=function(){ if(XHR.readystate==4&&XHR.status==200){ odiv.innerHTML=XHR.responseText; } } XHR.open("GET","ajax3.asp?"+str,true); XHR.send(); }</script><body><div id="responsetext"></div></body></html>