Load a CSS files asynchronously

load-css-js.js

/*! loadCSS: load a CSS file asynchronously. [c]2016 @scottjehl, Filament Group, Inc. Licensed MIT */
!function(e) {

    "use strict";

    var t = function(t, n, i) {
        var o, a = e.document,
            d = a.createElement("link"),
            r = i || "all";
        if (n) {
            o = n;
        } else {
            var l = (a.body || a.getElementsByTagName("head")[0]).childNodes;
            o = l[l.length - 1];
        }
        var s = a.styleSheets;
        d.rel = "stylesheet", d.href = t, d.media = "only x", o.parentNode.insertBefore(d, n ? o : o.nextSibling);
        var f = function(e) {
            for (var t = d.href, n = s.length; n--;) {
                if (s[n].href === t) {
                    return e();
                }
            }
            setTimeout(function() {
                f(e);
            });
        };
        return d.addEventListener && d.addEventListener("load", function() {
            this.media = r;
        }), d.onloadcssdefined = f, f(function() {
            d.media !== r && (d.media = r);
        }), d;
    };

    "undefined" !== typeof exports ? exports.loadCSS = t : e.loadCSS = t;

}("undefined" !== typeof global ? global : this);

/* CSS rel=preload polyfill (from src/cssrelpreload.js) */
(function(w) {

    "use strict";

    // rel=preload support test
    function support() {
        try {
            return w.document.createElement("link").relList.supports("preload");
        } catch (e) {}
    }

    // loop preload links and fetch using loadCSS
    function poly() {
        var links = w.document.getElementsByTagName("link");
        for (var i = 0; i < links.length; i++) {
            var link = links[i];
            if (link.rel === "preload" && link.getAttribute("as") === "style") {
                w.loadCSS(link.href, link);
                link.rel = null;
            }
        }
    }

    // if link[rel=preload] is not supported, we must fetch the CSS manually using loadCSS
    if (!support()) {
        poly();
        var run = w.setInterval(poly, 300);
        if (w.addEventListener) {
            w.addEventListener("load", function() {
                w.clearInterval(run);
            });
        }
    }

}(this));

(function(w) {

    'use strict';

    var doc = document,
        head = doc.getElementsByTagName('head')[0],
        s = 'string',
        f = false,
        push = 'push',
        readyState = 'readyState',
        onreadystatechange = 'onreadystatechange',
        list = {},
        ids = {},
        delay = {},
        scripts = {},
        scriptpath,
        urlArgs;

    var jsElements = doc.querySelectorAll('[data-js-src]'),
        jsCores = [],
        jsFinals = [];

    function every(ar, fn) {
        for (var i = 0, j = ar.length; i < j; ++i) {
            if (!fn(ar[i])) {
                return f;
            }
        }
        return 1;
    }

    function each(ar, fn) {
        every(ar, function(el) {
            return !fn(el);
        });
    }

    function create(path, fn) {
        var el = doc.createElement('script'),
            loaded;
        el.onload = el.onerror = el[onreadystatechange] = function() {
            if ((el[readyState] && !(/^c|loade/.test(el[readyState]))) || loaded) {
                return;
            }
            el.onload = el[onreadystatechange] = null;
            loaded = 1;
            scripts[path] = 2;
            fn();
        };
        // el.async = 1;
        el.src = urlArgs ? path + (path.indexOf('?') === -1 ? '?' : '&') + urlArgs : path;

        doc.body.appendChild(el);
        // head.insertBefore(el, head.lastChild);
    }

    function loadJS(paths, idOrDone, optDone) {
        paths = paths[push] ? paths : [paths];
        var idOrDoneIsDone = idOrDone && idOrDone.call,
            done = idOrDoneIsDone ? idOrDone : optDone,
            id = idOrDoneIsDone ? paths.join('') : idOrDone,
            queue = paths.length;

        function loopFn(item) {
            return item.call ? item() : list[item];
        }

        function callback() {
            if (!--queue) {
                list[id] = 1;
                done && done();
                for (var dset in delay) {
                    every(dset.split('|'), loopFn) && !each(delay[dset], loopFn) && (delay[dset] = []);
                }
            }
        }
        setTimeout(function() {
            each(paths, function loading(path, force) {
                if (path === null) {
                    return callback();
                }

                if (!force && !/^https?:\/\//.test(path) && scriptpath) {
                    path = (path.indexOf('.js') === -1) ? scriptpath + path + '.js' : scriptpath + path;
                }

                if (scripts[path]) {
                    if (id) {
                        ids[id] = 1;
                    }
                    return (scripts[path] === 2) ? callback() : setTimeout(function() { loading(path, true); }, 0);
                }

                scripts[path] = 1;
                if (id) {
                    ids[id] = 1;
                }
                create(path, callback);
            });
        }, 0);
        return loadJS;
    }

    loadJS.get = create;

    loadJS.order = function(scripts, id, done) {
        (function callback(s) {
            s = scripts.shift();
            !scripts.length ? loadJS(s, id, done) : loadJS(s, callback);
        }());
    };

    loadJS.done = function(idOrDone) {
        loadJS([null], idOrDone);
    };

    loadJS.path = function(p) {
        scriptpath = p;
    };

    loadJS.urlArgs = function(str) {
        urlArgs = str;
    };

    loadJS.ready = function(deps, ready, req) {
        deps = deps[push] ? deps : [deps];
        var missing = [];
        !each(deps, function(dep) {
                list[dep] || missing[push](dep);
            }) && every(deps, function(dep) {
                return list[dep];
            }) ?
            ready() : ! function(key) {
                delay[key] = delay[key] || [];
                delay[key][push](ready);
                req && req(missing);
            }(deps.join('|'));
        return loadJS;
    };

    if (jsElements.length) {

        var idx = 0;
        for (idx = 0; idx < jsElements.length; idx++) {

            var attrSrc = jsElements[idx].getAttribute('data-js-src'),
                attrDep = jsElements[idx].getAttribute('data-js-dep');

            if (attrDep !== 'korrekt') {
                jsFinals.push(attrSrc);
            } else {
                jsCores.push(attrSrc);
            }

        }

        loadJS(jsCores, function() {
            loadJS(jsFinals);
        });

    }

}(this));