Answer 1

maybe try:
for( var i=0; i < 3; i++)
m=rotate_90(m)

I don’t think this will fix the problem though, it should just make i a local variable, but maybe that’s the issue?

Answer 2

Indeed I tried with for(let i=0;i!=3...etc) and it worked ! Thank you Jackson O’Donnell !

Answer 3

Jackson O’Donnell sorry my question wasn't clear....
So in python it works but not in javascript: in javascript I believe that it runs forever because if I alert the output, that alert will never show up...

Answer 4

is the rotate_90(m) written in JS as well? It may be an issue in that function. And what is your error? Does it just not run? Run forever? Wrong output?