add 202-Happy-Number

Author: loczek

javascript/202-Happy-Number.js

@@ -0,0 +1,25 @@
+function isHappy(n) {
+  const visit = new Set();
+
+  while (!visit.has(n)) {
+    visit.add(n);
+    n = sumOfSquares(n);
+
+    if (n == 1) return true;
+  }
+
+  return false;
+}
+
+function sumOfSquares(n) {
+  let output = 0;
+
+  while (n) {
+    let digit = n % 10;
+    digit = digit ** 2;
+    output += digit;
+    n = Math.floor(n / 10);
+  }
+
+  return output;
+}