30-seconds-of-code/snippets/isArmstrongNumber.md

isArmstrongNumber

Checks if the given number is an Armstrong number or not.

Convert the given number into an array of digits. Use the exponent ** operator to get the appropriate power for each digit and sum them up. If the sum is equal to the number itself, return true otherwise false.

const isArmstrongNumber = digits =>
  (arr => arr.reduce((a, d) => a + parseInt(d) ** arr.length, 0) == digits)(
    (digits + '').split('')
  );

isArmstrongNumber(1634); // true
isArmstrongNumber(371); // true
isArmstrongNumber(56); // false