简单AJAX

/*--------------------------------------
Name: AJAXRequest
Version: 0.7.12
Author: xujiwei
E-mail: vipxjw@163.com
Website: http://www.xujiwei.cn
License: http://www.gnu.org/licenses/gpl.html GPL
Copyright (c) 2007, xujiwei, All Rights Reserved

AjaxRequest Deveoper Manual:
    http://ajax.xujiwei.cn/
--------------------------------------*/
function AJAXRequest() {
 var xmlPool=[],objPool=[],AJAX=this,ac=arguments.length,av=arguments;
 var xmlVersion=["MSXML2.XMLHTTP","Microsoft.XMLHTTP"];
 var eF=emptyFun=function(){};
 var av=ac>0?typeof(av[0])=="object"?av[0]:{}:{};
 var encode=$GEC(av.charset+"");
 this.url=getp(av.url,"");
 this.oncomplete=getp(av.oncomplete,eF);
 this.content=getp(av.content,"");
 this.method=getp(av.method,"POST");
 this.async=getp(av.async,true);
 this.onexception=getp(av.onexception,eF);
 this.ontimeout=getp(av.ontimeout,eF);
 this.timeout=getp(av.timeout,3600000);
 this.onrequeststart=getp(av.onrequeststart,eF);
 this.onrequestend=getp(av.onrequestend,eF);
 if(!getObj()) return false;
 function getp(p,d) { return p!=undefined?p:d; }
 function getObj() {
  var i,j,tmpObj;
  for(i=0,j=xmlPool.length;i<j;i++) if(xmlPool[i].readyState==0||xmlPool[i].readyState==4) return xmlPool[i];
  try { tmpObj=new XMLHttpRequest; }
  catch(e) {
   for(i=0,j=xmlVersion.length;i<j;i++) {
    try { tmpObj=new ActiveXObject(xmlVersion[i]); } catch(e2) { continue; }
    break;
   }
  }
  if(!tmpObj) return false;
  else { xmlPool[xmlPool.length]=tmpObj; return xmlPool[xmlPool.length-1]; }
 }
 function $(id){return document.getElementById(id);}
 function $N(d){var n=d*1;return(isNaN(n)?0:n);}
 function $VO(v){return(typeof(v)=="string"?(v=$(v))?v:false:v);}
 function $GID(){return((new Date)*1);}
 function $SOP(id,ct){objPool[id+""]=ct;}
 function $LOP(id){return(objPool[id+""]);}
 function $SRP(f,r,p){return(function(s){s=f(s);for(var i=0;i<r.length;i++) s=s.replace(r[i],p[i]);return(s);});}
 function $GEC(cs){
  if(cs.toUpperCase()=="UTF-8") return(encodeURIComponent);
  else return($SRP(escape,[/\+/g],["%2B"]));
 }
 function $ST(obj,text) {
  var nn=obj.nodeName.toUpperCase();
  if("INPUT|TEXTAREA".indexOf(nn)>-1) obj.value=text;
  else try{obj.innerHTML=text;} catch(e){};
 }
 function $CB(cb) {
  if(typeof(cb)=="function") return cb;
  else {
   cb=$VO(cb);
   if(cb) return(function(obj){$ST(cb,obj.responseText);});
   else return emptyFun; }
 }
 function $GP(p,v,d,f) {
  var i=0;
  while(i<v.length){p[i]=v[i]?f[i]?f[i](v[i]):v[i]:d[i];i++;}
  while(i<d.length){p[i]=d[i];i++;}
 }
 function send(purl,pc,pcbf,pm,pa) {
  var purl,pc,pcbf,pm,pa,ct,ctf=false,xmlObj=getObj(),ac=arguments.length,av=arguments;
  if(!xmlObj) return false;
  var pmp=pm.toUpperCase()=="POST"?true:false;
  if(!pm||!purl) return false;
  var ev={url:purl, content:pc, method:pm};
  purl+=(purl.indexOf("?")>-1?"&":"?")+"timestamp="+$GID();
  xmlObj.open(pm,purl,pa);
  AJAX.onrequeststart(ev);
  if(pmp) xmlObj.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
  ct=setTimeout(function(){ctf=true;xmlObj.abort();},AJAX.timeout);
  xmlObj.onreadystatechange=function() {
   if(ctf) { AJAX.ontimeout(ev); AJAX.onrequestend(ev); }
   else if(xmlObj.readyState==4) {
    ev.status=xmlObj.status;
    try{ clearTimeout(ct); } catch(e) {};
    try{ if(xmlObj.status==200) pcbf(xmlObj); else AJAX.onexception(ev); }
    catch(e) { AJAX.onexception(ev); }
    AJAX.onrequestend(ev);
   }
  }
  if(pmp) xmlObj.send(pc); else xmlObj.send("");
  return true;
 }
 this.setcharset=function(cs) { encode=$GEC(cs); }
 this.get=function() {
  var p=[],av=arguments;
  $GP(p,av,[this.url,this.oncomplete],[null,$CB]);
  if(!p[0]&&!p[1]) return false;
  return(send(p[0],"",p[1],"GET",this.async));
 }
 this.update=function() {
  var p=[],purl,puo,pinv,pcnt,av=arguments;
  $GP(p,av,[emptyFun,this.url,-1,-1],[$CB,null,$N,$N]);
  if(p[2]==-1) p[3]=1;
  var sf=function(){send(p[1],"",p[0],"GET",this.async);};
  var id=$GID();
  var cf=function(cc) {
   sf(); cc--; if(cc==0) return;
   $SOP(id,setTimeout(function(){cf(cc);},p[2]));
  }
  cf(p[3]);
  return id;
 }
 this.stopupdate=function(id) {
  clearTimeout($LOP(id));
 }
 this.post=function() {
  var p=[],av=arguments;
  $GP(p,av,[this.url,this.content,this.oncomplete],[null,null,$CB]);
  if(!p[0]&&!p[2]) return false;
  return(send(p[0],p[1],p[2],"POST",this.async));
 }
 this.postf=function() {
  var p=[],fo,vaf,pcbf,purl,pc,pm,ac=arguments.length,av=arguments;
  fo=ac>0?$VO(av[0]):false;
  if(!fo||(fo&&fo.nodeName!="FORM")) return false;
  vaf=fo.getAttribute("onvalidate");
  vaf=vaf?(typeof(vaf)=="string"?new Function(vaf):vaf):null;
  if(vaf&&!vaf()) return false;
  $GP(p,[av[1],fo.action,fo.method],[this.oncomplete,this.url,this.method],[$CB,null,null]);
  pcbf=p[0];purl=p[1];
  if(!pcbf&&!purl) return false;
  pc=this.formToStr(fo); if(!pc) return false;
  if(p[2].toUpperCase()=="POST")
   return(send(purl,pc,pcbf,"POST",true));
  else {
   purl+=(purl.indexOf("?")>-1?"&":"?")+pc;
   return(send(purl,"",pcbf,"GET",true));
  }
 }
 /* formToStr
 // from SurfChen <surfchen@gmail.com>
 // @url     http://www.surfchen.org/
 // @license http://www.gnu.org/licenses/gpl.html GPL
 // modified by xujiwei
 // @url     http://www.xujiwei.cn/
 */
 this.formToStr=function(fc) {
  var i,qs="",and="",ev="";
  for(i=0;i<fc.length;i++) {
   e=fc[i];
   if (e.name!='') {
    if (e.type=='select-one'&&e.selectedIndex>-1) ev=e.options[e.selectedIndex].value;
    else if (e.type=='checkbox' || e.type=='radio') {
     if (e.checked==false) continue;
     ev=e.value;
    }
    else ev=e.value;
    ev=encode(ev);
    qs+=and+e.name+'='+ev;
    and="&";
   }
  }
  return qs;
 }
}