soundbox | html5 audio player engine | Audio Utils library

I am trying to create a simple piano with all the sounds such as Do, Re, Mi etc using Vanilla Js. I am getting error regarding the querySelector function for data-* attribute. Here is the relevant part of my code.

I have created a splash screen for my android app,

in this activity I need to download some sounds from firebase storage and synchronized my local database with firebase realtime database.

but when I start the app, I see in my log the synchronization with firebase continue after the splash screen and the data is not in the locale database when the mainActivity is launch. Who to do for start the MainActivity aft the firebase synchronization is completed.

My code :

I work on an Android application and I need to download some Sound from firebase storage, I get the sound name from the firebase realtime database.

My code :

I'm currently working on a project for my computer science class and I'm having a problem. I have multiple buttons and 2 comboboxes and I want them all to work independently of each other. Unfortunately, whenever I press a button it works as a "select" button and activates whatever is currently selected in the combobox! How would I be able to solve this? A snippet of my code is below

Hello StackOverflow community, I would like to ask for some help as before asking I did a long research but found nothing to help me out.

I have a school project that I decided to code with Python using Kivy for cross-platform. My project is about a SoundBox, to simplify I need to first create buttons and bind them to play various sounds. On pure python code (without a .kv file), I learned how to bind a button to make it play a sound, so I decided to reach the next level that is the Screen Management part. I kind of learned that to using now a .kv file to make it simple but I'm stuck on how to bind a button using .kv file.

I tried out some stuff but always ended up with errors on the console, also (but it's not really important for now), my Fade Transition doesn't work. Your help is highly appreciated, thanks in advance.

.py: