en.javascript.info/1-js/02-first-steps/13-while-for/3-which-value-for/solution.md

The answer: from 0 to 4 in both cases.

for (let i = 0; i < 5; ++i) alert( i );

for (let i = 0; i < 5; i++) alert( i );

That can be easily deducted from the algorithm of for:

1. Execute once i = 0 before everything (begin).
2. Check the condition i < 5
3. If true -- execute the loop body alert(i), and then i++

The increment i++ is separated from the condition check (2). That's just another statement.

The value returned by the increment is not used here, so there's no difference between i++ and ++i.