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="/UploadFiles/2021-04-02/jquery-3.3.1.min.js">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 " ---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：
插件代码地址： https://gitee.com/muand/ajaxDown/tree/master/ajaxDown
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
