Persistent Bugger

6 kyu
Persistent Bugger.

Write a function, persistence, that takes in a positive parameter num and returns its multiplicative persistence, which is the number of times you must multiply the digits in num until you reach a single digit.

For example:

 persistence(39) === 3 // because 3*9 = 27, 2*7 = 14, 1*4=4
                       // and 4 has only one digit

 persistence(999) === 4 // because 9*9*9 = 729, 7*2*9 = 126,
                        // 1*2*6 = 12, and finally 1*2 = 2

 persistence(4) === 0 // because 4 is already a one-digit number
 
 
const persistence = (num, i = 0) => {

  if([...num.toString()].length === 1) return i;
  
  let numArr = [...num.toString()].reduce((acc, curr) => {
    return acc * +curr;
  })
  i++
  return persistence(numArr, i)
}


  console.log(persistence(39),3);
  console.log(persistence(4),0);
  console.log(persistence(25),2);