How do I solve this Javascript loop? [duplicate]

What will be the output of the following JavaScript code?

let a = 5;
let i;
for (i = 0; i < 3; i++) {
  console.log(a);
}

Stuck on this javascript question for a class. The answer is either 555 or error, but I truly have no idea what the answer is or why. Error because a isn’t anywhere in the for/equation?

Any help or insight is appriciated.