Progress bar that increments itself via a loop

fake_progress_bar.html

<div id="progress-bar"><div style="width:0;"></div>

<script>
  let progressBar = document.querySelector("#progress-bar div")
    let items = [];
    
    for (let index = 0; index <= 100; index++) {
        items.push(index);
    }
    
    delayedLoop(items, 10, function(item, index) {
        let width = (item / items.length * 100) + "%";
        progressBar.style.width = width;
    });
    
    function delayedLoop(collection, delay, callback, context) {
    context = context || null;

    let i = 0,
        nextInteration = function() {
            if (i === collection.length) {
                return;
            }

            callback.call(context, collection[i], i);
            i++;
            setTimeout(nextInteration, delay);
        };

    nextInteration();
}
</script>