Originally published on www.florin-pop.com

The theme for week #14 of the Weekly Coding Challenge is:

Progress Bar

A progress bar is used to show how far a user action is still in process until it's completed. A good example is a download progress bar which shows you how much of the file is downloaded already (or it could also be an upload progress bar if you upload files 🙂).

In this article we're going to build this kind of a Progress Bar:


For the HTML structure we need two things:

  1. a container which will display the total length (100%) of the progress bar - .progress-bar
  2. the actual progress element which will basically track the current progress (e.g. 20%) - .progress
<div class="progress-bar">
    <div data-size="20" class="progress"></div>

As you can see the .progress div has a data-size attribute. This will be used in JavaScript to actually set the width of the progress. You'll see in a moment what I mean, but first let's style these two elements. 😄


.progress-bar {
    background-color: #fefefe;
    border-radius: 3px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
    margin: 15px;
    height: 30px;
    width: 500px;
    max-width: 100%;

.progress {
    background: #ad5389;
    background: -webkit-linear-gradient(to bottom, #3c1053, #ad5389);
    background: linear-gradient(to bottom, #3c1053, #ad5389);
    border-radius: 3px;
    height: 30px;
    width: 0;
    transition: width 0.5s ease-in;

Few things to note regarding the above CSS:

  1. both elements are rectangles that have the same height (30px) and the same border-radius
  2. initially the .progress width it set to 0 and we'll update this in the JavaScript code below
  3. also the .progress has a nice linear-gradient from uiGradients
  4. the transition added to the .progress is used to create a nice animation when the value of it's data-size attribute is dynamically changed

The JavaScript

For this we'll need to loop over all the .progress elements (in our example is only one, but you can add multiple ones in an app) to get their data-set value and to set it as their width. We'll use percentage (%) in this case.

const progress_bars = document.querySelectorAll('.progress');

progress_bars.forEach(bar => {
    const { size } = bar.dataset;
    bar.style.width = `${size}%`;

We're using a little bit of Object Destructuring.

const { size } = bar.dataset

is the same as:

const size = bar.dataset.size

but you might know that already 😉.


There are multiple things you could do to improve this component. Some of which are:

  1. Add multiple color variants via different classes
  2. Add the percentage value
  3. Make it animate dynamically by changing the size value.

I hope you enjoyed it and make sure you share with me what you're creating!

Happy Coding! 😇