创建XHR对象
兼容IE7已经更高的版本:
function createXHR(){ if(typeof XMLHttpRequest != "undefind"){ return new XMLHttpRequest(); }else if(typeof ActiveXObject != "undefind"){ var versions = ["MSXML2.XMLHttp.6.0","MSXML2.XMLHttp.3.0","MSXML2.XMLHttp"], len = versions.length; for(var i = 0; i < len; i ++){ try{ new ActiveXObject(versions[i]); arguments.callee.activeXString = versions[i]; break; }catch(e){ console.log(e); } } }else{ throw new Errow("NO XHR object"); } }
var xhr = createXHR();
XHR的用法
方法:
1. open()
启动一个请求必备发送:
xhr.open("get", "demo.php", false);
三个参数:
- 请求的类型 get / post
- url
- 同步(false)或者异步(true), 默认为异步
2. send()
请求发送服务器:
xhr.send(null)
属性:
1. responseText
从服务器返回的文本
2. responseXML
3. status
相应的HTTP状态
4. statusText
HTTP状态的说明
同步情况下可以:
xhr.open("get", "demo.php", false); xhr.send(null); if(xhr.status >=200 && xhr.status < 300 || xhr.status == 304){ console.log(xhr.responseText); }else{ console.log("Request was unsuccessful: " + xhr.status ); }
一般我们都是异步:
var xhr = createXHR(); xhr.onreadystatuschange = function(){ if(xhr.readyStatus == 4){ if((xhr.status >= 200 && xhr.status < 300) || xhr.status == 304){ console.log(xhr.responseText); }else{ console.log("Request was unsuccessful: " + xhr.status); } } }; xhr.open("get", "demo", true); xhr.send(null);
请求方式
1. GET
参数的拼接:
url + "?" + "名1=值1" + "&" + "名2=值2" + .....
xhr.open("get", "demo.php?name1=value1&name2=value2", true);
2. POST