Implementing JS' Math.pow functional

pow.js

// recursive
const pow = (base, expo) => 
  expo === 1 
    ? base 
    : base * pow(base, expo - 1);

// tail recursive
const pow = (base, expo, _result = base) => 
  expo === 1 
    ? _result 
    : pow(base, expo - 1, base * _result);

// reduce
const pow = (base, expo) => 
  Array(expo).fill(base).reduce((r, v) => r * v);