ajax小封装

	var ajax=new Object();
	var request=false;
	ajax.create=function(){
		if(window.XMLHttpRequest){
			request= new XMLHttpRequest;
			//有些浏览器需要设置mime类型，如果存在重写mime类型的属性就进行设置
			if(request.overrideMimeType) {
				request.overrideMimeType('text/xml');
			}	
		}else if(window.ActiveXObject){
		　　　　 //搞定兼容性
			var versions = ['Microsoft.XMLHTTP', 'MSXML.XMLHTTP', 'Microsoft.XMLHTTP', 'Msxml2.XMLHTTP.7.0', 'Msxml2.XMLHTTP.6.0', 'Msxml2.XMLHTTP.5.0', 'Msxml2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP'];
			for(i=0;i<versions.length;i++){
				try{
					request=new ActiveXObject(versions[i]);
					if(request){
						return request;
					}
				}catch(e){
				
					request=false;
				}	
			}
		}
		return request;
	}
	ajax.request=ajax.create();
	ajax.get=function(url,func){
		ajax.request.open('get',url);
		ajax.request.send(null);
		ajax.onreadystatechange(func);		
	}
	ajax.post=function(url,data,func){
		ajax.request.open('post',url);
		ajax.request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
		ajax.request.send(data);
	}
　　　　　//回调函数
	ajax.onreadystatechange=function(func){
		ajax.request.onreadystatechange=function(){
			if(ajax.request.readyState==4){
				if(ajax.request.status==200){
					func(ajax.request.responseText);
				}
			}	
		}
	}