js 的 ajax 实现

需要或者不需要返回值得ajax函数封装


 /**
 * 原生的ajax封装 
 * param     :
 * url     :
 * data     :
 * success    :
 * cache     :
 */
 var ajax = function(param){
  typeof param === "object";
 
  for(var i in param){
   param[i] = param[i] === undefined ? "" : param[i] ;
  }
 
  var ajax = window.XMLHttpRequest ?
      new XMLHttpRequest() :
      new ActiveXObject('Microsoft.XMLHTTP');
   
 
  if(    typeof param.data === "object" ){
   var urli = "";
   for (var i in param.data)
    urli += "&"+i+"="+param.data[i];
  }
  param.url += param.url.indexOf("?") > 0 ? urli :
    (urli.replace(/^\&(.+)/,"?$1"));
   
 
  ajax.onreadystatechange = function() {
   if (ajax.readyState === 4 && ajax.status === 200) {
    param.success && param.success(ajax.responseText);
    ajax.onreadystatechange = function(){};
   };
  };
  ajax.open('GET', param.url, (param.asy ? 0 : 1));
  ajax.send(null);
 }
 
 
 ajax({
  url:"ajax.common.php",
  data:{"school":"江西"},
  success:function(msg){
   alert(msg)
  }
 })