Guarantee mixpanel is loaded

mp_async_queue.js

<script type="text/javascript">
// mixpanel stub and initialization
(function(e,b){if(!b.__SV){var a,f,i,g;window.mixpanel=b;b._i=[];b.init=function(a,e,d){function f(b,h){var a=h.split(".");2==a.length&&(b=b[a[0]],h=a[1]);b[h]=function(){b.push([h].concat(Array.prototype.slice.call(arguments,0)))}}var c=b;"undefined"!==typeof d?c=b[d]=[]:d="mixpanel";c.people=c.people||[];c.toString=function(b){var a="mixpanel";"mixpanel"!==d&&(a+="."+d);b||(a+=" (stub)");return a};c.people.toString=function(){return c.toString(1)+".people (stub)"};i="disable track track_pageview track_links track_forms register register_once alias unregister identify name_tag set_config people.set people.set_once people.increment people.append people.track_charge people.clear_charges people.delete_user".split(" ");
for(g=0;g<i.length;g++)f(c,i[g]);b._i.push([a,e,d])};b.__SV=1.2;a=e.createElement("script");a.type="text/javascript";a.async=!0;a.src=("https:"===e.location.protocol?"https:":"http:")+'//cdn.mxpnl.com/libs/mixpanel-2.2.min.js';f=e.getElementsByTagName("script")[0];f.parentNode.insertBefore(a,f)}})(document,window.mixpanel||[]);

var callbacks = [];
var mixpanelIsLoaded = false;
var withMixpanel = function(callback) {
	callbacks.push(callback);
	flushQueue();
}

var flushQueue = function() {
	if (mixpanelIsLoaded) {
		for(var i = 0; i < callbacks.length; i++) {
			callbacks[i]();
		}
	}
}

var mixpanelLoadedCallback = function() {
	mixpanelIsLoaded = true;
	flushQueue();
}

// now you can guarantee that mixpanel has been fully initialized
withMixpanel(function() {
	alert(mixpanel.get_distinct_id());
})

withMixpanel(function() { 
	mixpanel.track('boom');	
})

mixpanel.init('1ef7e30d2a58d27f4b90c42e31d6d7ad', {loaded: mixpanelLoadedCallback})
</script>