DEV Community

Discussion on: Write a script to find "Happy Numbers"

View post

Replies for: function isHappy(n) { if (n === 4) return false; const u = n.toString().split('').reduce(((ac,cv) => ac + Math.pow(cv,2)), 0); if (u...

Collapse
 
prodigalknight profile image
RevanProdigalKnight • • Edited

Your code in ES2016+ (and a bit less readable):

const isHappy = n => {
  if (n === 4) return false;

  const u = [...n.toString()].reduce((ac, c) => ac + (c ** 2), 0);

  return u === 1 || isHappy(u);
};
Collapse
 
nickytonline profile image
Nick Taylor •

You could even shorten the toString by replacing it with a template string which will do an implicit toString.

const isHappy = n => {
  if (n === 4) return false;

  const u = [...`${n}`].reduce((ac, c) => ac + (c ** 2), 0);

  return u === 1 || isHappy(u);
};