JS questions for a newbie

Great! Glad you're getting stuck in!

As @Ganblejs says I'd ignore Fast load for now - it shaves maybe 300ms off the time to switch to the launcher from the clock, so in most cases it won't be a big deal.

Often when I'm developing I comment out the { and } right at the beginning and end of fast load clocks anyway:

{ // this
let x = ...
...
} // this

It means that when you've uploaded your clock you can use the left-hand side of the IDE to manually check what's in variables or to call functions if you want to