currying.js

function curry(func, length = func.length) {
  // passing a second paramenter as the number of arguments
  // passed to the function
  return function (...args) {
    if (args.length >= length) {
      // if the function call contains arguments which are 
      // greater than or equal to the max, just the return the func
      return func(...args);
    } else {
      // otherwise call the curry again, binding the already
      // appeared arguments and this time, decreasing the length of agruments by 
      // number of arguments passed earlier
      return curry(func.bind(this, ...args), length - args.length);
    }
  };
}

function add(a, b, c) {
  return a + b + c
}

const curryAdd = curry(add);

console.log(curryAdd(3,4,5)) // 12
console.log(curryAdd(4,5)(4)) // 13