5-curry.js

'use strict';

// Check 4 digit pin.
const EXPECTED_PIN = '4967';
const checkPin = (...code) => code.join('') === EXPECTED_PIN;

// Define function curry that accepts the length of the function
// (amount of function arguments) and the function.
// prettier-ignore
const curry =
  (length, fn) =>
    (...args) => {
      if (length > args.length) {
        const f = fn.bind(null, ...args);
        return curry(length - 1, f);
      } else {
        return fn(...args);
      }
    };

// Allows to enter pin code by one character,
// Usage: press('3')('4')('5')('6')
const press = curry(4, checkPin);

module.exports = { press };