Custom Script

I implement this solution in the Wappler project: https://jsfiddle.net/68y2b53w/5/

My implementation looks like this:

For some reason, when calling the function in the script, there is a problem with dmx. The transitionend event listener also doesn’t work:

Note that if you call the showSizes() function using a static event (for example, when a button is clicked), the function works stably.

However, I need the resize_h variable to update its value every time the size of the messageArea element changes.

What prevents this script from working in the Wappler?