Taken from https://medium.com/@samerbuna/coding-tip-try-to-code-without-if-statements-d06799eed231

doubler.js

const doubler = (input) => {
  return doubler.operationsByType[typeof input](input);
};
doubler.operationsByType = {
  number: (input) => input + input,
  string: (input) =>
    input
      .split('')
      .map((letter) => letter + letter)
      .join(''),
  function: (input) => {
    input();
    input();
  },
  object: (input) => {
    Object.keys(input)
          .map((key) => (input[key] = doubler(input[key])));
    return input;
  },
};