如何创建XMLHttpRequest包装器/代理？ [英] How can I create a XMLHttpRequest wrapper/proxy?

问题描述

想到这些方法，每种方法的优缺点是什么？

These methods that come to mind, what are the pros and cons of each?

方法1：增加原生实例

var _XMLHttpRequest = XMLHttpRequest;
XMLHttpRequest = function() {
    var xhr = new _XMLHttpRequest();

    // augment/wrap/modify here
    var _open = xhr.open;
    xhr.open = function() {
        // custom stuff
        return _open.apply(this, arguments);
    }

    return xhr;
}

方法2：子类本机XMLHttpRequest

Method 2: Sub-"class" native XMLHttpRequest

var _XMLHttpRequest = XMLHttpRequest;
XMLHttpRequest = function() {
    // definePropertys here etc
}

XMLHttpRequest.prototype = new _XMLHttpRequest());
// OR
XMLHttpRequest.prototype = Object.create(_XMLHttpRequest);

// custom wrapped methods on prototype here
XMLHttpRequest.prototype.open = function() {
    // custom stuff
    return _XMLHttpRequest.prototype.open.apply(this, arguments);
}

方法3：原生XMLHttpRequest的完全代理

Method 3: Full proxy to native XMLHttpRequest

var _XMLHttpRequest = XMLHttpRequest;
XMLHttpRequest = function() {
    this.xhr = new _XMLHttpRequest();
}

// proxy ALL methods/properties
XMLHttpRequest.prototype.open = function() {
    // custom stuff
    return this.xhr.open.apply(this.xhr, arguments);
}

推荐答案

取决于JS引擎，方法1产生相当大的开销，因为只要XHR被实例化，就会重新定义 xhr.open 。

Depending on the JS engine, method 1 produces considerable overhead, since xhr.open is redefined whenever XHR is instantiated.

方法2让我思考为什么你首先需要 new _XMLHttpRequest ？有一种不良副作用的轻微感觉，但看起来效果很好。

Method 2 makes me think "why would you need the new _XMLHttpRequest in the first place"? There's a minor feeling of undesired side effects, but it appears to work just fine.

方法3：简单，老派，但它不会直接起作用。 （考虑阅读属性）

Method 3: simple, old-school, but it won't work straight-away. (Think about reading properties)

一般来说，在覆盖浏览器对象时我个人不情愿，所以这对所有三种方法都是一个很大的帮助。更好地使用其他变量，如 ProxyXHR （只需我2美分）

In general, I'm personally reluctant when it comes to overwriting browser objects, so that would be a big con to all three methods. Better use some other variable like ProxyXHR (just my 2 cents)

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