Async Twig Macros

macros.html

{% macro asyncCSS(urls) %}
	{% for url in urls %}asyncCSS({{ url }});{% endfor %}
	function asyncCSS(url) {
		var wf = document.createElement('link');
		wf.href = ('https:' == document.location.protocol ? 'https:' : 'http:') + url;
		wf.rel = 'stylesheet';
		wf.media = 'only x';
		var s = document.getElementsByTagName('style')[0];
		s.parentNode.insertBefore(wf, s);
	}
{% endmacro %}

{% macro asyncJS(urls) %}
	{% for url in urls %}asyncJS({{ url }});{% endfor %}
	function asyncJS(url) {
		var wf = document.createElement('script');
		wf.src = ('https:' == document.location.protocol ? 'https:' : 'http:') + url;
		wf.type = 'text/javascript';
		wf.async = 'true';
		var s = document.getElementsByTagName('script')[0];
		s.parentNode.insertBefore(wf, s);
	}
{% endmacro %}