Javascript - Delaying module return/declaration in Require.js?

http://stackoverflow.com/questions/18749604/javascript-delaying-module-return-declaration-in-require-js

by fiddlegrimbo

HTML

<script>
    require = {
        paths: {
            "when": "https://rawgithub.com/cujojs/when/2.4.0/when"
        }
    };
</script>
<script src="http://requirejs.org/docs/release/2.1.8/comments/require.js"></script>

JavaScript

// --------------------------------------------------
// New module
// Using https://github.com/cujojs/when/wiki/Examples
// --------------------------------------------------

define("my-ajax", ["when"], function (when) {
    // TODO - Fake id only for testing
    var id = 0;

    function makeFakeJSFiddleRequestData(fileName) {
        var data = {
            fileName: fileName
        };
        data = "json=" + encodeURI(JSON.stringify(data));
        var delayInSeconds = Math.floor(8 * Math.random());
        data += "&delay=" + delayInSeconds;
        return data;
    }

    return function loadJSON(args) {
        // Create the deferred response
        var deferred = when.defer();

        var xhr = new XMLHttpRequest();
        xhr.overrideMimeType("application/json");

        var url = args.fileName;

        // TODO - Override URL only for testing
        url = "/echo/json/";

        // TODO - Provide request data and timings only for testing
        var start = +new Date();
        var data = makeFakeJSFiddleRequestData(args.fileName);

        // TODO - POST for testing. jsfiddle expects POST.
        xhr.open("POST", url, true);

        xhr.onreadystatechange = function () {
            // TODO - duration only for testing.
            var duration = +new Date() - start + "ms";
            if (xhr.readyState == 4) {
                if (xhr.status === 200) {
                    // Check that response is valid JSON
                    var json;
                    try {
                        json = JSON.parse(xhr.responseText);
                    } catch (e) {
                        console.log("rejected", args, duration);
                        deferred.reject(e);
                        return;
                    }
                    console.log("resolved", args, duration);
                    // TODO - Fake id only for testing
                    json.id = ("id" + id++);
                    deferred.resolve(json);
                } else...