javascript 当任何 XMLHttpRequest 完成时如何运行函数？
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How to run a function when any XMLHttpRequest is complete?
提问by MCM
I'm working on a project that has several scripts that I cannot change. These scripts update the page via AJAX. When the update is complete I need to run some code.
我正在处理一个项目，该项目有几个我无法更改的脚本。这些脚本通过 AJAX 更新页面。更新完成后，我需要运行一些代码。
Is there any event that fires when any XMLHttpRequest is complete? (or any XMLHttpRequest state change?).
当任何 XMLHttpRequest 完成时，是否会触发任何事件？（或任何 XMLHttpRequest 状态更改？）。
Unfortunately I cannot access the specific XMLHttpRequest object used to make the request.
不幸的是，我无法访问用于发出请求的特定 XMLHttpRequest 对象。
Thanks,
谢谢，
回答by apsillers
Without jQuery, you can hook the openmethod to attach a listener for each XHR object's readystatechangeevents at the time the XHR object is opened. Ensure the following code runs before any Ajax occurs:
如果没有 jQuery，您可以挂钩该open方法，以便readystatechange在open编辑XHR 对象时为每个 XHR 对象的事件附加一个侦听器。确保在任何 Ajax 发生之前运行以下代码：
// save the real open
var oldOpen = XMLHttpRequest.prototype.open;
function onStateChange(event) {
// fires on every readystatechange ever
// use `this` to determine which XHR object fired the change event
}
XMLHttpRequest.prototype.open = function() {
// when an XHR object is opened, add a listener for its readystatechange events
this.addEventListener("readystatechange", onStateChange)
// run the real `open`
oldOpen.apply(this, arguments);
}
Alternatively, if you only care about successful loadevents, you can listener for that event instead of readystatechange.
或者，如果您只关心成功的load事件，则可以侦听该事件而不是readystatechange.
