JSFiddle - React, Tailwind, and code Playground

by Tim Ko

JavaScript

// Happy numbers
// https://en.wikipedia.org/wiki/Happy_number

function isHappyNumber(n) {
	var visited = {};
	while (true) {
		n = n.toString().split('').map(s => parseInt(s)).map(d => d * d).reduce((s, d) => s + d, 0);
		if (n === 1) {
    	return true;
    } else if (n in visited) {
    	return false;
    } else {
    	visited[n] = true;
    }
  }
}

console.log(isHappyNumber(15)); // false
console.log(isHappyNumber(68)); // true