Add Euclidean GCD algo

Author: tshemsedinov

JavaScript/9-gcd.js

@@ -0,0 +1,10 @@
+'use strict';
+
+const gcd = (a, b) => {
+  if (b === 0) return a;
+  return gcd(b, a % b);
+};
+
+// const gcd = (a, b) => (b === 0 ? a : gcd(b, a % b));
+
+console.log(gcd(12, 78));