simple curry in javascript

curry.js

function sum(a, b, c, d, e) {
  console.log(a, b, c, d, e);
  return a + b + c + d + e;
}

function curry(fn) {
  let total = fn.length;
  function inner(a) {
    --total;
    if (total === 0) {
      return fn.call(null, a);
    }
    fn = fn.bind(null, a);
    return inner;
  }

  return inner;
}

const sumOfAll = curry(sum);
console.log(sumOfAll(1)(2)(3)(4)(5));