persistence function 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.

my solution :

const persistence = num => {
  return `${num}`.length > 1 
    ? 1 + persistence(`${num}`.split('').reduce((a, b) => a * +b)) 
    : 0;
}

 

 

 

 

const persistence = num => {
  return `${num}`.length > 1 
    ? 1 + persistence(`${num}`.split('').reduce((a, b) => a * +b)) 
    : 0;
}