Armstrong numbers

typescript/armstrong-numbers/armstrong-numbers.ts

@@ -0,0 +1,8 @@
+export const isArmstrongNumber = (candidate: bigint | number): boolean => 
+   candidate
+    .toString()
+    .split('')
+    .map(BigInt)
+    .reduce((result, value, _index, arr) =>
+      result + (value ** BigInt(arr.length)), 0n
+    ) === BigInt(candidate);