var fitie = function (node) {
    // restrict to valid object-fit value
    var objectFit = node.currentStyle['object-fit'];

    if (!objectFit || !/^(contain|cover|fill)$/.test(objectFit)) return;

    var setCSS = node.runtimeStyle;
    var getCSS = node.currentStyle;
    node.defaultStyle = node.defaultStyle || [];

    if (node.defaultStyle === []) {
        for (var key in getCSS) {
            node.defaultStyle[key] = getCSS[key];
        }
    }

    if (node.parentNode.nodeName.toLowerCase() === 'object-fit') {
        node.parentNode.parentNode.replaceChild(node, node.parentNode);
        for (var key in node.defaultStyle) {
            setCSS[key] = node.defaultStyle[key];
        }
    }

    // prepare container styles
    var outerWidth = node.clientWidth;
    var outerHeight = node.clientHeight;
    var outerRatio = outerWidth / outerHeight;

    var name = node.nodeName.toLowerCase();

    var addEventListener = node.addEventListener || node.attachEvent;
    var removeEventListener = node.removeEventListener || node.detachEvent;
    var on = node.addEventListener ? '' : 'on';
    var img = name === 'img';
    var type = img ? 'load' : 'loadedmetadata';

    addEventListener.call(node, on + type, onload);

    if (node.complete) onload();

    function onload() {
        removeEventListener.call(node, on + type, onload);

        // prepare container styles
        var imgCSS = {
            boxSizing: 'content-box',
            display: 'inline-block',
            overflow: 'hidden'
        };

        'backgroundColor backgroundImage borderColor borderStyle borderWidth bottom fontSize lineHeight height left opacity margin position right top visibility width'.replace(/\w+/g, function (key) {
            imgCSS[key] = getCSS[key];
        });

        // prepare image styles
        setCSS.border = setCSS.margin = setCSS.padding = 0;
        setCSS.display = 'block';
        setCSS.height = setCSS.width = 'auto';
        setCSS.opacity = 1;

        var innerWidth = node.videoWidth || node.width;
        var innerHeight = node.videoHeight || node.height;
        var innerRatio = innerWidth / innerHeight;

        // style container
        var imgx = document.createElement('object-fit');

        if (node.parentNode.nodeName.toLowerCase() !== 'object-fit') {
            imgx.appendChild(node.parentNode.replaceChild(imgx, node));

            for (var key in imgCSS) {
                node.defaultStyle[key] = imgCSS[key];
            }
        } else {
            var oldImgx = node.parentNode;
            var parent = oldImgx.parentNode;

            imgx = document.createElement('object-fit');
            imgx.appendChild(node);
            parent.replaceChild(imgx, oldImgx);
        }

        for (var key in node.defaultStyle) imgx.runtimeStyle[key] = node.defaultStyle[key];

        // style image
        var newSize;

        if (objectFit === 'fill') {
            if (img) {
                setCSS.width = outerWidth;
                setCSS.height = outerHeight;
            } else {
                setCSS['-ms-transform-origin'] = '0% 0%';
                setCSS['-ms-transform'] = 'scale(' + outerWidth / innerWidth + ',' + outerHeight / innerHeight + ')';
            }
        } else if (innerRatio < outerRatio ? objectFit === 'contain' : objectFit === 'cover') {
            newSize = outerHeight * innerRatio;

            setCSS.width = Math.round(newSize) + 'px';
            setCSS.height = outerHeight + 'px';
            setCSS.marginLeft = Math.round((outerWidth - newSize) / 2) + 'px';
        } else {
            newSize = outerWidth / innerRatio;

            setCSS.width = outerWidth + 'px';
            setCSS.height = Math.round(newSize) + 'px';
            setCSS.marginTop = Math.round((outerHeight - newSize) / 2) + 'px';
        }
    }
};
fitie.init = function () {
    if (document.body) {
        var all = document.querySelectorAll('img,video');
        var index = -1;

        while (all[++index]) fitie(all[index]);

        window.addEventListener("resize", fitie.init); //TODO: optimize to run time consuming code only if width is actually changed...
    } else {
        setTimeout(fitie.init);
    }
};

if (/MSIE|Trident/.test(navigator.userAgent)) fitie.init();

Uncaught TypeError: Cannot set property 'init' of undefined