Javascript function executed in this pattern "xyz()()" throws error?

Question

 var recursiveSum = function() {
    console.log(arguments.length);
 }
 recursiveSum(1)(2)(3);

Why is it throwing not a function error? I am using NodeJs to execute above sript.

Answer 1

It would only work if recursiveSum would return a function.

Right now, you try to execute the return value of recursiveSum(1) as a function. It isn't (it's undefined), and thus an error is thrown; you try to execute undefined(2)(3).

You could do something like this.

function currySum(x) {
  return function(y) {
    return function(z) {
      return x + y + z;
    }
  }
}

console.log(currySum(1)(2)(3));