Browser XHR Spy

xhr-spy.js

/**
 * The following code, when executed in a browser's JS console,
 * will log detailed information about every XHR made from the 
 * web page. Perfect for spying on API calls.
 */
(function() {
    var XHR = XMLHttpRequest.prototype;
    // Remember references to original methods
    var open = XHR.open;
    var send = XHR.send;

    // Overwrite native methods
    // Collect data: 
    XHR.open = function(method, url) {
        this._method = method;
        this._url = url;
        return open.apply(this, arguments);
    };

    // Implement "ajaxSuccess" functionality
    XHR.send = function(postData) {
        this.addEventListener('load', function() {
            this._body = postData;
            console.log(this);
        });
        return send.apply(this, arguments);
    };
})();