jQuery $(document).ready() in vanilla JavaScript

jquery-document-ready-vanilla-javascript.js

/*
    https://developer.mozilla.org/en-US/docs/Web/API/Window/DOMContentLoaded_event
    - The DOMContentLoaded event fires when the initial HTML document has been completely loaded and parsed,
    without waiting for stylesheets, images, and subframes to finish loading.
    - A different event, load, should be used only to detect a fully-loaded page. 

    https://developer.mozilla.org/en-US/docs/Web/API/Document/readyState    
    - loading: The document is still loading.
    - interactive: The document has finished loading and the document has been parsed but sub-resources such as scripts, images, stylesheets and frames are still loading.
    - completeThe document and all sub-resources have finished loading. The state indicates that the load event is about to fire.
*/

function doOnDocumentLoaded () {
    loaderInit();
    carouseslInit();
}

if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', doOnDocumentLoaded);
} else {
    doOnDocumentLoaded();
}