問題描述

想到的這些方法，各有什么優(yōu)缺點?

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

方法一:增強原生實例

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:子類"原生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);
}

方法三:完全代理原生 XMLHttpRequest

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);
}

推薦答案

根據(jù) JS 引擎，方法 1 會產(chǎn)生相當(dāng)大的開銷，因為每當(dāng)實例化 XHR 時都會重新定義 xhr.open.

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

方法 2 讓我想為什么首先需要 new _XMLHttpRequest"?有輕微副作用的感覺，但似乎效果很好.

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:簡單、老派，但不會立即奏效.(考慮讀取屬性)

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

一般來說，我個人不太愿意覆蓋瀏覽器對象，所以這對所有三種方法來說都是一個很大的缺點.最好使用其他變量，例如 ProxyXHR(只是我的 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)

這篇關(guān)于如何創(chuàng)建 XMLHttpRequest 包裝器/代理?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！