Conditionally load zepto or jQuery with yepnope

gistfile1.js

var zep = "__proto__" in window;

yepnope([{
    test:     zep,
    yep:      '/static/js/zepto.js',
    nope:     '//ajax.googleapis.com/ajax/libs/jquery/1.8.1/jquery.min.js',
    complete: function () {
        !zep && !window.jQuery && yepnope('/static/js/jquery-1.8.1.min.js');
    }
});