JSONP (not perfect)

jsonp.js

var pendingsJsonpCbs = [];

var jsonp = function(uri, cb) {
    pendingsJsonpCbs.push(cb);
    var scriptEl = document.createElement('script');
    scriptEl.setAttribute('type', 'text/javascript');
    scriptEl.setAttribute('src', uri + '&jsonp=parseJSON');
    document.head.appendChild(scriptEl);
};

var parseJSON = function(o) {
    pendingsJsonpCbs.shift()(o);
};