Как подвязаться к чужому ajax запросу?

ajaxCatchUp().then(function(data) {
	console.log(data);
});

function ajaxCatchUp() {
	var promise = $.Deferred();
	$(document).on('ajaxComplete', function(event, jqXHR) {
		jqXHR.done(promise.resolve).fail(promise.reject);
	});
	return promise;
}

requestCatchUp(function(data) {
	console.log(data);
});

function requestCatchUp(success, error) {
	proxyRequest('open', function() {
		this.onreadystatechange = function() {
			if (this.readyState === 4) {
				if (this.status >= 200 && this.status < 400) {
					if (success) {
						var data = (function() {
							try {
								return JSON.parse(this.responseText);
							} catch (err) {
								return this.responseText;
							}
						}.bind(this))();
						success.call(this, data);
					}
				} else {
					if (error) error.call(this);
				}
			}
		};
		return this;
	});
}

function proxyRequest(method, callback) {
	(function(native) {
		XMLHttpRequest.prototype[method] = function() {
			native.apply(callback.apply(this, arguments), arguments);
		};
	})(XMLHttpRequest.prototype[method]);
}