JSONP-global.js

// Adds one JSONP global (for requireJS module, see JSONP.js)
var JSONP = (function (global) {
    // (C) WebReflection Essential - Mit Style
    // cleaned up by Brett Zamir for JSLint and avoiding additional globals and need for conventional [?&]callback= in URL)
    'use strict';
    var id = 0,
        ns = 'JSONP',
        prefix = '__JSONP__',
        document = global.document,
        documentElement = document.documentElement;
    return function (uri, callback) {
        var src = prefix + id++,
            script = document.createElement('script'),
            JSONPResponse = function () {
                try { delete global[ns][src]; } catch(e) { global[ns][src] = null; }
                documentElement.removeChild(script);
                callback.apply(this, arguments);
            };
        global[ns][src] = JSONPResponse;
        documentElement.insertBefore(
            script,
            documentElement.lastChild
        ).src = uri + (uri.indexOf('?') > -1 ? '&' : '?') + 'callback=' + ns + '.' + src;
    };
}(this));

JSONP.js

/*globals define */
define(function () {
    // (C) WebReflection Essential - Mit Style
    // cleaned up by Brett Zamir for JSLint and avoiding additional globals and need for conventional [?&]callback= in URL)
    'use strict';
    var id = 0,
        global = this,
        ns = 'JSONP',
        prefix = '__JSONP__',
        document = global.document,
        documentElement = document.documentElement;
    return function (uri, callback) {
        var src = prefix + id++,
            script = document.createElement('script'),
            JSONPResponse = function () {
                try { delete global[ns][src]; } catch(e) { global[ns][src] = null; }
                documentElement.removeChild(script);
                callback.apply(this, arguments);
            };
        global[ns][src] = JSONPResponse;
        documentElement.insertBefore(
            script,
            documentElement.lastChild
        ).src = uri + (uri.indexOf('?') > -1 ? '&' : '?') + 'callback=' + ns + '.' + src;
    };
});

MediaWikiJSONP.js

/*globals define */
define(['JSONP'], function MediaWikiJSONP(baseURL, argObj, cb) {
    var uri, arg, args = '';
    if (!cb) {
        cb = argObj;
        argObj = null;
    }
    for (arg in argObj) {
        args += '&' + arg + '=' + encodeURIComponent(argObj[arg]);
    }
    uri = baseURL +  '/w/api.php?format=json' + args;
    JSONP(uri, cb);
});