Curry function to find sum of integers with different parameter usage

Sum Curry function with extensibility

function sum() {
  let args = [...arguments];
  if (args.length > 2) {
    let sumValue = 0;
    args.forEach(arg => {
      sumValue += arg;
    });
    return sumValue;
  }
  if (args.length === 2) {
    return function() {
      return sum.apply(this, [...args, ...arguments]);
    };
  }

 function single() {
    if (arguments.length === 0) {
      return sum.apply(this, args);
    }
    args = [...args, ...arguments];
    return single;
  };
  return single;
}


console.log(sum(2, 3, 4));
console.log(sum(2, 3)(4));
console.log(sum(2, 3, 4, 0, 1));
console.log(sum(2)(3)(4)());
console.log(sum(2)(3)(4)(0)(1)());