javascript写一个ajax自动拦截并下载数据代码实例

更新时间：2020-09-11 17:42:01 作者：startmvc

这篇文章主要介绍了javascript写一个ajax自动拦截并下载数据代码实例,文中通过示例代码介绍

这篇文章主要介绍了javascript写一个ajax自动拦截并下载数据代码实例,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

代码如下


<!DOCTYPE html>
<html lang="zh">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title></title>
</head>
<body>
</body>
<script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>
<script type="text/javascript">
// 自动下载 ajax 的脚本
;(function($,flag,host){
 if(!flag){
 //如果关闭下载数据,则什么也不做,否则会拦截 ajax 请求返回的数据,进行下载
 return ;
 }
 var ajax = $.ajax; //缓存原始的 ajax
 $.ajax = function(opt){
 var success = opt.success || function(){};
 var url = opt.url || "";
 opt.success = function(res){
 try{
 var name = url.split("?")[0];
 if(host){
 name = name.replace(host,"");
 }
 name = name.replace(/\//g,"_");
 downData(res,`${name}.json`);
 }catch(e){
 console.warn(e);
 }
 success(res);
 }
 return ajax(opt);
 }
 function downData(data,name){
 if(typeof data == "object"){
 data = JSON.stringify(data);
 }
 var blob = new Blob([data], {
 type: 'text/html,charset=UTF-8' 
 });
 window.URL = window.URL || window.webkitURL;
 var a = document.createElement("a");
 a.setAttribute("download",name || "data.json");
 a.href = URL.createObjectURL(blob);
 a.click();
 }
})($,true,"https://www.easy-mock.com");
 
//自动下载数据
$.ajax({
 url:"https://www.easy-mock.com/mock/5bb02bc0a0afc503f502a292/example/demo/secret",
 success(res){
 console.log(res);
 }
})
</script>
</html>

使用原生的 xhr 和fetch 拦截


// 自动下载 ajax 的脚本
 // 命名空间
 window.ajax_interceptor_manny = {
 settings: {
 switchOn: false,
 switchQuery:false
 },
 originalXHR: window.XMLHttpRequest,
 myXHR: function() {
 console.log(" ---ajax 拦截--- ")
 let pageScriptEventDispatched = false;
 const modifyResponse = () => {
 //this.responseText = overrideTxt;
 //this.response = overrideTxt;
 if (pageScriptEventDispatched) {
 return;
 }
 pageScriptEventDispatched = true;
 ajax_interceptor_manny.download(this.responseText, this.responseURL);
 }
 
 // new 一个原生的 XMLHttpRequest 不需要参数,将 xhr 的属性,都复制给this,暴露到外面
 const xhr = new ajax_interceptor_manny.originalXHR();
 
 for (let attr in xhr) {
 if (attr === 'onreadystatechange') {
 xhr.onreadystatechange = (...args) => {
 if (this.readyState == 4 && this.status == 200) {
 // 请求成功
 if (ajax_interceptor_manny.settings.switchOn) {
 // 开启拦截
 modifyResponse();
 }
 }
 this.onreadystatechange && this.onreadystatechange.apply(this, args);
 }
 continue;
 } else if (attr === 'onload') {
 xhr.onload = (...args) => {
 // 请求成功
 if (ajax_interceptor_manny.settings.switchOn) {
 // 开启拦截
 modifyResponse();
 }
 this.onload && this.onload.apply(this, args);
 }
 continue;
 }
 
 if (typeof xhr[attr] === 'function') {
 this[attr] = xhr[attr].bind(xhr);
 } else {
 if (attr === 'responseText' || attr === 'response') {
 var k = "_"+attr;
 Object.defineProperty(this, attr, {
 get: () => this[k] == undefined ? xhr[attr] : this[k],
 set: (val) => this[k] = val,
 });
 } else {
 Object.defineProperty(this, attr, {
 get: () => xhr[attr],
 set: (val) => xhr[attr] = val,
 });
 }
 }
 }
 },
 originalFetch: window.fetch.bind(window),
 myFetch: function(...args) {
 console.log(" ---fetch 拦截--- ")
 return ajax_interceptor_manny.originalFetch(...args).then((response) => {
 if (response.ok) {
 response.clone().text().then((res) => {
 ajax_interceptor_manny.download(res, response.url);
 }).catch((e) => {
 console.warn(e)
 });
 }
 return response;
 });
 },
 download(data, url) {
 try {
 if (ajax_interceptor_manny.settings.switchOn) {
 if (typeof data == "object") {
 data = JSON.stringify(data);
 }
 var blob = new Blob([data], {
 type: 'text/html,charset=UTF-8'
 });
 window.URL = window.URL || window.webkitURL;
 
 var name = url;
 if(!(url.indexOf("http://") >= 0 || url.indexOf("https://") >= 0)){
 //不存在域名
 url = window.origin + url; //手动添加一个，避免URL解析出错
 }
 try {
 var u = new URL(url);
 name = u.pathname;
 var search = u.search.replace("?","");
 if(ajax_interceptor_manny.settings.switchQuery && search){
 //需要带上 get 参数
 name = name + "$"+ search;
 }
 } catch (e) {console.warn(e)}
 name = name.replace(new RegExp("//","g"),"/");
 name = name.replace(new RegExp("/","g"), "_");
 name = name + ".json";
 var a = document.createElement("a");
 a.setAttribute("download", name || "data.json");
 a.href = URL.createObjectURL(blob);
 a.click();
 }
 } catch (e) {
 console.error("下载数据失败", e);
 }
 
 },
 
 setSetting(data) {
 if (typeof data !== "object") {
 return;
 }
 //设置环境
 for (var i in data) {
 ajax_interceptor_manny.settings[i] = data[i];
 }
 },
 init() {
 window.XMLHttpRequest = ajax_interceptor_manny.myXHR;
 window.fetch = ajax_interceptor_manny.myFetch;
 }
 }
ajax_interceptor_manny.init();
ajax_interceptor_manny.setSetting({
 switchOn:true
})

还可以将这个拦截，写为一个浏览插件：