Don't use a return statement in a callback to return a value because it's not possible to get the value in the addEventListener.
JavaScript: advanced
You are writing many times "trackEl.innerHTML = 'something';", what about making a function that accepts a string as param and paints it into 'trackEl'?
[ ] You are writing many times document.querySelector(".js-result"); make a var
Good practices
Write your code in English!
Try to use imperative for functions names.
Make multiple commits as you work.
HTML
Add form
Define a good structure of folders and files for the project.
Further challenges
Then you can improve the game as you please, here you have some ideas:
Check if the player has enough money to bet and if the bet is greater than 0 and lower than the current amount of the player.
Add a reset button that cleans the select, balance of money and writes the initial feedback.
Show the restart game button when the game is over and hide the play button.
Complete the code needed for the restart game button.
Validates if the balance of money is available is less than the money bet and displays a message
Whatever you want!
Call to action
Let me know if you have any doubts ;)
Go for it!!
Do not close this issue until your teacher asks you to