Lazy load de imágenes (con soporte responsive)

scripts.js

/**
Alternativa de menos de 1kb: https://apoorv.pro/lozad.js/demo/
*/

document.addEventListener('DOMContentLoaded', function () {
    var bLazy = new Blazy({
        src: 'data-src',
        selector: '*[data-src]',
        offset: 500,
        breakpoints: [
            {width: 1024, src: 'data-src'},
            {width: 1920, src: 'data-desktop'}
        ]
    });

});