Asynchronous script and/or stylesheet loader

script-css-loader.js

!function() {
    "use strict";
    var loader = function(assets) {
        if (Object.prototype.toString.call(assets) !== "[object Array]" && assets.length < 1) {
            return;
        }
        //  get asset
        var assetSrc = assets.shift();
        //  determine asset type
        var assetType = (assetSrc.indexOf(".css") !== -1) ? "script" : "style";
        //  create elements style/script
        var elm = document.createElement(assetType);
        var head = document.getElementsByTagName("head")[0];
        //  set asset attributes
        if (assetType === "script") {
            elm.src = assetSrc;
            elm.async = "true";
        } else {
            elm.href = assetSrc;
            elm.rel = "stylesheet";
        }
        head.appendChild(elm);
        //  load until assets array is empty
        loader();
    }
    //  normalize environments
    if (typeof define === "function" && define.amd) {
        define(function() { return loader; });
    } else if (module && module.exports) {
        module.exports = loader;
    } else {
        self.loader = loader;
    }
}();
//  usage
var assets = ["script.js", "style.css"];
window.loader(assets);