sprite-async.js

// ==========================================================================
// SVG sprite loading
// This file should be at the top of the body to avoid a flash
// ==========================================================================

// Loading SVG in with AJAX
// ---------------------------------
(function(url) {
	var id = "svg-sprite",
	cb = (window.location.host.indexOf("local.") === 0);

	// Cache busting locally
	if(cb) {
		url += "?" + Math.floor(Math.random() * 1001);
	}

	// Respect protocol for IE9
	// http://stackoverflow.com/a/8509981/1191319
	if(window.location.protocol === "http:") {
		url = url.replace("https", "http");
	}

	// Only load once
	if(document.querySelectorAll("#" + id).length === 0) {
		var xhr = new XMLHttpRequest(),
		body = document.body;

		// Create container
		var container = document.createElement("div");
		container.setAttribute("hidden", "");
		container.setAttribute("id", id);

		// XHR for Chrome/Firefox/Opera/Safari
		if ("withCredentials" in xhr) {
			xhr.open("GET", url, true);
		}
		// XDomainRequest for older IE
		else if(typeof XDomainRequest != "undefined") {
			xhr = new XDomainRequest();
			xhr.open("GET", url);
		}
		// Not supported
		else {
			return;
		}

		// Once loaded, inject to container and body
		xhr.onload = function() {
			container.innerHTML = xhr.responseText;

			// Inejct the SVG to the body
			body.insertBefore(container, body.childNodes[0]);
		};

		// Timeout for IE9
		setTimeout(function () {
			xhr.send();
		}, 0);
	}
})(config.cdn.assets + "/sprite.svg");