Question

This is the code without any attempt to add var nn = 99 to the loop

//note that the 'i' is a parameter of the function
function myFunction(arr, i) {
  for (i = i ? i + 5 : 1; i < arr.length; i++) {
    //...
  }
}

When I try to add a new var it do things I don’t want:

Edit: it seems this is wrong

for (var nn = 99, i = i ? i + 5 : 1; i < arr.length; i++)
//created a new 'i'

or

for (i = i ? i + 5 : 1, var nn = 99; i < arr.length; i++)
//doesn't work :(

I know it is exactly the same if I move it outside. But one of the things I hate most, is to not be able to understand what I meant when reading a old code after some months. Moving that line inside the loop will make me understand that line easier.

Answer 1

You can’t modify the function’s parameter. As i is a primitive value (number), JavaScript will call-by-value, not by-reference.

And as you name your second argument “i”, it will be available as a local variable from start on. Using the var keyword with “i” somewhere won’t change anything.