Ajax hook is a lightweight library for intercepting XMLHttpRequest objects.
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/450907/1090926/Ajax-hook-userscript.js
// ==UserScript==
// @name Ajax-hook-userscript
// @namespace https://github.com/wendux/Ajax-hook
// @version 2.0.3
// @author wendux
// @description Ajax hook is a lightweight library for intercepting XMLHttpRequest objects.
// @license MIT
// @grant unsafeWindow
// @run-at document-start
// ==/UserScript==
const ah = (W => {
/*
* author: wendux
* email: 824783146@qq.com
* source code: https://github.com/wendux/Ajax-hook
* modify by https://github.com/lzghzr
*/
// Save original XMLHttpRequest as _rxhr
var realXhr = "_rxhr"
function configEvent(event, xhrProxy) {
var e = {};
for (var attr in event) e[attr] = event[attr];
// xhrProxy instead
e.target = e.currentTarget = xhrProxy
return e;
}
function hook(proxy) {
// Avoid double hookAjax
W[realXhr] = W[realXhr] || W.XMLHttpRequest
W.XMLHttpRequest = function () {
var xhr = new W[realXhr];
// We shouldn't hookAjax XMLHttpRequest.prototype because we can't
// guarantee that all attributes are on the prototype。
// Instead, hooking XMLHttpRequest instance can avoid this problem.
for (var attr in xhr) {
var type = "";
try {
type = typeof xhr[attr] // May cause exception on some browser
} catch (e) {
}
if (type === "function") {
// hookAjax methods of xhr, such as `open`、`send` ...
this[attr] = hookFunction(attr);
} else {
Object.defineProperty(this, attr, {
get: getterFactory(attr),
set: setterFactory(attr),
enumerable: true
})
}
}
var that = this;
xhr.getProxy = function () {
return that
}
this.xhr = xhr;
}
// Generate getter for attributes of xhr
function getterFactory(attr) {
return function () {
var v = this.hasOwnProperty(attr + "_") ? this[attr + "_"] : this.xhr[attr];
var attrGetterHook = (proxy[attr] || {})["getter"]
return attrGetterHook && attrGetterHook(v, this) || v
}
}
// Generate setter for attributes of xhr; by this we have an opportunity
// to hookAjax event callbacks （eg: `onload`） of xhr;
function setterFactory(attr) {
return function (v) {
var xhr = this.xhr;
var that = this;
var hook = proxy[attr];
// hookAjax event callbacks such as `onload`、`onreadystatechange`...
if (attr.substring(0, 2) === 'on') {
that[attr + "_"] = v;
xhr[attr] = function (e) {
e = configEvent(e, that)
var ret = proxy[attr] && proxy[attr].call(that, xhr, e)
ret || v.call(that, e);
}
} else {
//If the attribute isn't writable, generate proxy attribute
var attrSetterHook = (hook || {})["setter"];
v = attrSetterHook && attrSetterHook(v, that) || v
this[attr + "_"] = v;
try {
// Not all attributes of xhr are writable(setter may undefined).
xhr[attr] = v;
} catch (e) {
}
}
}
}
// Hook methods of xhr.
function hookFunction(fun) {
return function () {
var args = [].slice.call(arguments)
if (proxy[fun]) {
var ret = proxy[fun].call(this, args, this.xhr)
// If the proxy return value exists, return it directly,
// otherwise call the function of xhr.
if (ret) return ret;
}
return this.xhr[fun].apply(this.xhr, args);
}
}
// Return the real XMLHttpRequest
return W[realXhr];
}
function unHook() {
if (W[realXhr]) W.XMLHttpRequest = W[realXhr];
W[realXhr] = undefined;
}
/*
* author: wendux
* email: 824783146@qq.com
* source code: https://github.com/wendux/Ajax-hook
*/
var events = ['load', 'loadend', 'timeout', 'error', 'readystatechange', 'abort'];
var eventLoad = events[0],
eventLoadEnd = events[1],
eventTimeout = events[2],
eventError = events[3],
eventReadyStateChange = events[4],
eventAbort = events[5];
var singleton,
prototype = 'prototype';
function proxy(proxy) {
if (singleton) throw "Proxy already exists";
return singleton = new Proxy(proxy);
}
function unProxy() {
singleton = null
unHook()
}
function trim(str) {
return str.replace(/^\s+|\s+$/g, '');
}
function getEventTarget(xhr) {
return xhr.watcher || (xhr.watcher = document.createElement('a'));
}
function triggerListener(xhr, name) {
var xhrProxy = xhr.getProxy();
var callback = 'on' + name + '_';
var event = configEvent({ type: name }, xhrProxy);
xhrProxy[callback] && xhrProxy[callback](event);
var evt;
if (typeof (Event) === 'function') {
evt = new Event(name, { bubbles: false });
} else {
// https://stackoverflow.com/questions/27176983/dispatchevent-not-working-in-ie11
evt = document.createEvent('Event');
evt.initEvent(name, false, true);
}
getEventTarget(xhr).dispatchEvent(evt);
}
function Handler(xhr) {
this.xhr = xhr;
this.xhrProxy = xhr.getProxy();
}
Handler[prototype] = Object.create({
resolve: function resolve(response) {
var xhrProxy = this.xhrProxy;
var xhr = this.xhr;
xhrProxy.readyState = 4;
xhr.resHeader = response.headers;
xhrProxy.response = xhrProxy.responseText = response.response;
xhrProxy.statusText = response.statusText;
xhrProxy.status = response.status;
triggerListener(xhr, eventReadyStateChange);
triggerListener(xhr, eventLoad);
triggerListener(xhr, eventLoadEnd);
},
reject: function reject(error) {
this.xhrProxy.status = 0;
triggerListener(this.xhr, error.type);
triggerListener(this.xhr, eventLoadEnd);
}
});
function makeHandler(next) {
function sub(xhr) {
Handler.call(this, xhr);
}
sub[prototype] = Object.create(Handler[prototype]);
sub[prototype].next = next;
return sub;
}
var RequestHandler = makeHandler(function (rq) {
var xhr = this.xhr;
rq = rq || xhr.config;
xhr.withCredentials = rq.withCredentials;
xhr.open(rq.method, rq.url, rq.async !== false, rq.user, rq.password);
for (var key in rq.headers) {
xhr.setRequestHeader(key, rq.headers[key]);
}
xhr.send(rq.body);
});
var ResponseHandler = makeHandler(function (response) {
this.resolve(response);
});
var ErrorHandler = makeHandler(function (error) {
this.reject(error);
});
function Proxy(proxy) {
var onRequest = proxy.onRequest,
onResponse = proxy.onResponse,
onError = proxy.onError;
function handleResponse(xhr, xhrProxy) {
var handler = new ResponseHandler(xhr);
if (!onResponse) return handler.resolve();
var ret = {
response: xhrProxy.response,
status: xhrProxy.status,
statusText: xhrProxy.statusText,
config: xhr.config,
headers: xhr.resHeader || xhr.getAllResponseHeaders().split('\r\n').reduce(function (ob, str) {
if (str === "") return ob;
var m = str.split(":");
ob[m.shift()] = trim(m.join(':'));
return ob;
}, {})
};
onResponse(ret, handler);
}
function onerror(xhr, xhrProxy, e) {
var handler = new ErrorHandler(xhr);
var error = { config: xhr.config, error: e };
if (onError) {
onError(error, handler);
} else {
handler.next(error);
}
}
function preventXhrProxyCallback() {
return true;
}
function errorCallback(xhr, e) {
onerror(xhr, this, e);
return true;
}
function stateChangeCallback(xhr, xhrProxy) {
if (xhr.readyState === 4 && xhr.status !== 0) {
handleResponse(xhr, xhrProxy);
} else if (xhr.readyState !== 4) {
triggerListener(xhr, eventReadyStateChange);
}
return true;
}
return hook({
onload: preventXhrProxyCallback,
onloadend: preventXhrProxyCallback,
onerror: errorCallback,
ontimeout: errorCallback,
onabort: errorCallback,
onreadystatechange: function (xhr) {
return stateChangeCallback(xhr, this);
},
open: function open(args, xhr) {
var _this = this;
var config = xhr.config = { headers: {} };
config.method = args[0];
config.url = args[1];
config.async = args[2];
config.user = args[3];
config.password = args[4];
config.xhr = xhr;
var evName = 'on' + eventReadyStateChange;
if (!xhr[evName]) {
xhr[evName] = function () {
return stateChangeCallback(xhr, _this);
};
}
var defaultErrorHandler = function defaultErrorHandler(e) {
onerror(xhr, _this, configEvent(e, _this));
};
[eventError, eventTimeout, eventAbort].forEach(function (e) {
var event = 'on' + e;
if (!xhr[event]) xhr[event] = defaultErrorHandler;
});
// 如果有请求拦截器，则在调用onRequest后再打开链接。因为onRequest最佳调用时机是在send前，
// 所以我们在send拦截函数中再手动调用open，因此返回true阻止xhr.open调用。
//
// 如果没有请求拦截器，则不用阻断xhr.open调用
if (onRequest) return true;
},
send: function (args, xhr) {
var config = xhr.config
config.withCredentials = xhr.withCredentials
config.body = args[0];
if (onRequest) {
// In 'onRequest', we may call XHR's event handler, such as `xhr.onload`.
// However, XHR's event handler may not be set until xhr.send is called in
// the user's code, so we use `setTimeout` to avoid this situation
var req = function () {
onRequest(config, new RequestHandler(xhr));
}
config.async === false ? req() : setTimeout(req)
return true;
}
},
setRequestHeader: function (args, xhr) {
// Collect request headers
xhr.config.headers[args[0].toLowerCase()] = args[1];
return true;
},
addEventListener: function (args, xhr) {
var _this = this;
if (events.indexOf(args[0]) !== -1) {
var handler = args[1];
getEventTarget(xhr).addEventListener(args[0], function (e) {
var event = configEvent(e, _this);
event.type = args[0];
event.isTrusted = true;
handler.call(_this, event);
});
return true;
}
},
getAllResponseHeaders: function (_, xhr) {
var headers = xhr.resHeader
if (headers) {
var header = "";
for (var key in headers) {
header += key + ': ' + headers[key] + '\r\n';
}
return header;
}
},
getResponseHeader: function (args, xhr) {
var headers = xhr.resHeader
if (headers) {
return headers[(args[0] || '').toLowerCase()];
}
}
});
}
return {
proxy,
unProxy,
hook,
unHook,
}
})(typeof unsafeWindow === 'undefined' ? window : unsafeWindow);