当任何 XMLHttpRequest 完成时如何运行函数?

问题描述

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.

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.

当任何 XMLHttpRequest 完成时是否会触发任何事件?(或任何 XMLHttpRequest 状态更改?).

Is there any event that fires when any XMLHttpRequest is complete? (or any XMLHttpRequest state change?).

不幸的是，我无法访问用于发出请求的特定 XMLHttpRequest 对象.

Unfortunately I cannot access the specific XMLHttpRequest object used to make the request.

谢谢，

推荐答案

不使用 jQuery，您可以挂钩 open 方法来为每个 XHR 对象的 readystatechange 事件附加一个监听器在 XHR 对象被 opened 时.确保在发生任何 Ajax 之前运行以下代码:

Without jQuery, you can hook the open method to attach a listener for each XHR object's readystatechange events at the time the XHR object is opened. Ensure the following code runs before any Ajax occurs:

// 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);
}

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.

Alternatively, if you only care about successful load events, you can listener for that event instead of readystatechange.

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