Can you explain pls?

Question

I've little knowledge about js. That's why I'm unable to understand output. it's not my code. it's copy from SL.

https://code.sololearn.com/Wte3Ds8E07Ra/?ref=app

Answer 1

the first one will always be 0 because you multiply with 0 at the beginning

the second code starts at 1 and adds the following values to it

0, 1, 2, 3

=> 7