jellyfin-web/dashboard-ui/bower_components/emby-lazyload-image/lazyload-image.html

<script>

    require(['imageFetcher'], function (imageFetcher) {
        window.ImageFetcherLazyloadImage = imageFetcher;
    });

    /**
     * <lazyload-image>
     * HTMLImageElement extension for lazy loading.
     * http://github.com/1000ch/lazyload-image
     *
     * Copyright 1000ch
     * licensed under the MIT license.
     */
    window.LazyloadImage = (function () {
        'use strict';

        var FALLBACK_IMAGE = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAEElEQVR42gEFAPr/AP///wAI/AL+Sr4t6gAAAABJRU5ErkJggg==';

        // create prototype from HTMLImageElement
        var LazyloadImagePrototype = Object.create(HTMLImageElement.prototype);

        // lifecycle callbacks
        //LazyloadImagePrototype.createdCallback = function () {

        //};

        //LazyloadImagePrototype.attachedCallback = function () {

        //    var original = this.currentSrc || this.src;

        //    if (original && window.ImageFetcherLazyloadImage) {
        //        //console.log(original);
        //        this.src = FALLBACK_IMAGE;
        //        console.log('loading ' + original);
        //        ImageFetcherLazyloadImage.loadImage(this, original);
        //    }
        //};

        return document.registerElement('lazyload-image', {
            prototype: LazyloadImagePrototype,
            extends: 'img'
        });

    })();

</script>