简述ajax的js原生实现过程_原生JS写Ajax的请求函数功能

一般我们写网页的时候，如果用到 Ajax 请求服务器，都是使用 JQuery 等已经封装好的库来调用，比较简单。

但是一般这些库的功能很多，引入了太多我们用不到的东西，如果我们需要写一个功能单一，简单的页面，完全用不到引用如此庞大的库文件。

我们可以简单实现一个自己的 Ajax 请求功能，具体的代码如下：

var ajax = {};
ajax.x = function () {
 if (typeof XMLHttpRequest !== "undefined") {
 return new XMLHttpRequest();
 }
 var versions = [
 "MSXML2.XmlHttp.6.0",
 "MSXML2.XmlHttp.5.0",
 "MSXML2.XmlHttp.4.0",
 "MSXML2.XmlHttp.3.0",
 "MSXML2.XmlHttp.2.0",
 "Microsoft.XmlHttp"
 ];
 var xhr;
 for (var i = 0; i < versions.length; i++) {
 try {
 xhr = new ActiveXObject(versions[i]);
 break;
 } catch (e) {
 }
 }
 return xhr;
};
ajax.send = function (url, method, data, success,fail,async) {
 if (async === undefined) {
 async = true;
 }
 var x = ajax.x();
 x.open(method, url, async);
 x.onreadystatechange = function () {
 if (x.readyState == 4) {
 var status = x.status;
 if (status >= 200 && status < 300) {
 success && success(x.responseText,x.responseXML)
 } else {
 fail && fail(status);
 }
 }
 };
 if (method == "POST") {
 x.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
 }
 x.send(data)
};
ajax.get = function (url, data, callback, fail, async) {
 var query = [];
 for (var key in data) {
 query.push(encodeURIComponent(key) + "=" + encodeURIComponent(data[key]));
 }
 ajax.send(url + (query.length ? "?" + query.join("&") : ""), "GET", null, callback, fail, async)
};
ajax.post = function (url, data, callback, fail, async) {
 var query = [];
 for (var key in data) {
 query.push(encodeURIComponent(key) + "=" + encodeURIComponent(data[key]));
 }
 ajax.send(url,"POST", query.join("&"), callback, fail, async)
};

使用方法： GET

ajax.get("/test.php", {foo: "bar"}, function(response,xml) {
 //success
},
function(status){
 //fail
});
POST
ajax.post("/test.php", {foo: "bar"}, function(response,xml) {
 //succcess
},function(status){
 //fail
});

这里需要注意一个问题，如果我们想要发送类似

var sendCmd = "?op_code=" + code + "&op_cmd=" + cmd;
ajax.post("/control" + sendCmd,"",function(response,xml) {
 console.log("success");
},
function(status){
 console.log("failed:" + status);
});

简述ajax的js原生实现过程_原生JS写Ajax的请求函数功能

http://m.bbyears.com/wangyezhizuo/143884.html

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