CSS is one of my favorite types of way to design, knowing a bit of Javascript helps with this tremendously to make my ideas come to life. What’s more, I love using [Flexbox]https://css-tricks.com/snippets/css/a-guide-to-flexbox/) within CSS.

This project (a course taught by Wes Bos ) is a way to present images in a smooth animated way.

The Flex Panels demo

See the Pen Flex Panels Image Gallery by scott thigpen (@sthig) on CodePen.


In setting up this project I had to add some Flexbox to the css. There are several panels in this project named .panel and I want to evenly space them across the screen. Easy peasy with taking the css class .panels and adding display: flex;

.panels {
	overflow: hidden;
	display: flex;

Then to evenly space them out across the screen I added flex: 1; to .panel

.panel {
      box-shadow:inset 0 0 0 5px rgba(255,255,255,0.1);
      text-align: center;

This is great however the items (the text in this case) is all at the top so I need to get that centers vertically and horizontally. So to do that I need to add some flexbox alignment AND make the children of .panel display flex as well. We do this by adding this to the element:

.panel {
	justify-content: center;
	align-items: center;
	display: flex;}

Children, behave!

CSS is full of fun little tricks, grabbing elements with a few commands really helps here.

.panel > *:first-child { transform: translateY(-100%); }
.panel > *:last-child { transform: translateY(100%); }

When you use the > sign and say “first (or last) child”, the code above will get only the first or last children and translate their positions on the Y axis thus moving them off screen for our project.

Flexing your muscles

The last part of the CSS setup is that when a panel is being clicked on, it should expand while the others stay small. To do this we’ll take the class of .open and add flex: 5;, this means that when the open class is assigned, it will take up 5 times more than any other panel.

The Javascript

The last part to this puzzle is the javascript which is the fun part (and for me, the challenging part).

The first part is to do a query selector all and grab all the panels with this line:

const panels = document.querySelectorALL('.panels');

(document.querySelectorAll will get anything with the class you tell it to grab, here it’d be .panels)

The next part is to write the function that will toggle the classes to transition the words in and out of our project, we do this by writing:

function toggleOpen() {

From there we’ll write a forEach loop that listens for a click (or when a user clicks on a panel) and we’ll do that by writing an event listener.

panels.forEach(panel => panel.addEventListener(‘click’, toggleOpen));

To break this down, our variable (const) “panels” is being looped over forEach one listening for a click, when clicked, run the function “toggleOpen”.

From there we run the function and boom, things work… they just don’t end

Looking for transitions

There are many transitions that happen as the function ends, we’re looking for a particular one, for that we write another function

    function toggleActive(e) {
      if(e.propertyNamelincludes('flex')) {

This function will grab an event (e in the (argument) of the function) and if the event includes the word flex, then toggle the class .open active

This will then return everything back it’s original state.