Reduce-Accumulator is not working as i understand reduce- Javascript

1

I dont understand how the accumulator is working here in this simple reduce function. i understand accumulator is that after each iteration the accumulator value will be passed to the next iteration, i was expecting some thing like this … Any idea please if i am missing something here.

  • Expected output as i understand reduce function
hellois odd // this return will be the accumulator for the next iteration
hellois odd  is even // this return will be the accumulator for the next iteration
hellois odd  is even is odd // this return will be the accumulator for the next iteration
hellois odd  is even is odd is even // this return will be the accumulator for the next iteration
  • Reduce function on array17
const array17 = [1, 2, 3, 4];

function Evenodd(acc, element) {
  if (element % 2 == 0) return `${acc}is even \n`;
  else if (element % 3 == 0 && element % 2 != 0) {
    return `${acc}is odd \n`;
  } else if (element == 1) {
    return `${acc}is odd \n`;
  }
}

console.log(array17.reduce(Evenodd, "hello"));
  • Actual output in console
hellois odd 
is even
is odd
is even
2

so if i do in step wise.

1- Even odd the callback function is called with at first with accumulator as “hello” and element as 1 and the return is hello is odd.

2-the return in the above statement will be as accumulator in this iteration and here the accululator is hello is odd and the return will be hello is odd is even
… this is my understanding of reduce function… if i am not missing something here…

but the output is coming as
1- hello is odd
2- is odd
3- is odd
4- is even

3

What you’re thinking about the iterations is right. I think what you’re missing is that the strings include a new line character (\n). This means your output isn’t 4 different logs, its one log with 4 new lines

1- hellois odd \n
is even \n
is odd \n
is even \n
2 Likes
4

Thats the point i missed was all of the output is actually one log after it finish with last iteration.
Thanks Senocular, you are always helpful :slight_smile:

1 Like