原生ajax请求之前端

前端发送ajax请求，并采用restful风格。

    var xhr = createXHR();
    
    xhr.onreadystatechange =  function(){
        if(xhr.readyState === 4){
            if ((xhr.status >= 200 && xhr.status < 300) || xhr.status == 304){ //success
                //console.log(xhr.responseText);
                //成功之后的操作
                gridStore.setData( JSON.parse(xhr.responseText) );
                            
            } else { 
                console.log("Request was unsuccessful: " + xhr.status); 
            }
        }
    };
    
    xhr.open('get','diana',true);  //第三个参数 ，是否异步
    xhr.send(null); 




    function createXHR(){
        if (typeof XMLHttpRequest != "undefined"){ 
            return new XMLHttpRequest();
        } else if (typeof ActiveXObject != "undefined"){ 
            if (typeof arguments.callee.activeXString != "string"){ 
                var versions = [ "MSXML2.XMLHttp.6.0", "MSXML2.XMLHttp.3.0", "MSXML2.XMLHttp"],
                i, len;

                for (i=0,len=versions.length; i < len; i++){ 
                    try { 
                        new ActiveXObject(versions[i]);
                        arguments.callee.activeXString = versions[i]; 
                        break;
                    } catch (ex){ 
                    //跳过
                    } 
                } 
            } 

            return new ActiveXObject(arguments.callee.activeXString); 
            
        } else {
            throw new Error("No XHR object available.");
        } 
     }     

以上便是原生ajax请求的简单使用。