Dynamically embedding Gists

async-gists.js

document.addEventListener("DOMContentLoaded", function(event) {
	
	document.write = function (code) {
		
		var gistURL, div, a, style;
		
		// create a <div> element to search gist url
		div = document.createElement('div')
		div.innerHTML = code
		
		// get gist url from code
		if(a = div.querySelector( "div.gist-meta a" )) {
			gistURL = a.getAttribute('href')
		}	
		
		// search for <script> tag and update gist code
		if(gistURL) {
			var gistID = gistURL.replace(/\/raw(.)*/, '').replace(/^(.)*gist.github.com\/([^\/]+)\//, '');
			document.querySelectorAll('script').forEach(function (item) {
				
				var scriptURL = item.getAttribute('src');
				
				if(scriptURL && scriptURL.match(new RegExp('^(.)*gist.github.com\/([^\/]+)\/'+gistID))) {
					item.outerHTML = code;
				}
			});
		}
		// include CSS
		else if (!document.write.cssIncluded){
			document.write.cssIncluded = 1;
			style = document.createElement('div')
			style.innerHTML = code
			document.getElementsByTagName("head")[0].appendChild(style.childNodes[0]);
		}
		
	}	
});