Loops variables declaration

Question

Does declaring variables of a loop (such as i, j) out side the loop itself affect how loops work by any means (specially when looping through nested arrays "arrays inside an array" ) caused I faced a challenge that somehow my code didn't work until I declared my loop variables inside the for() brackets ?!! 🤷

Answer 1

Are you resetting the inner loop variable back to the original definition once the inner loop is done iterating?

https://code.sololearn.com/WHPluES92XWY/#html

https://www.w3schools.com/js/js_loop_for.asp

Answer 2

ODLNT now I get it, thank you a lot

Answer 3

It depends how you declare it.

If you declare the variable with let in the for-line, it won't be available anymore after the loop ended.

If you define it with var, it's the same as if you had declared it before the loop - it will be available outside and in the loop.

Answer 4

@HongFu I declared it firstly with var at the top of my code .. but it didn't work, (I think it worked only on the 1st subarray but neglected the others) then when I changed that to declaring it inside the for () brackets it worked
https://edabit.com/challenge/ve7mQnJsjtFep97fm
Here's a link of the challenge try to do it with declaring before using loops and it won't work (I know the challenge could be solved with high order functions 😅 but it's what it's)