How can I make var a = add(2)(3); //5 work?

Question

I want to make this syntax possible:

var a = add(2)(3); //5

based on what I read at http://dmitry.baranovskiy.com/post/31797647

I\

Answer 1

we can do this work using closure.

    function add(param1){
      return function add1(param2){
      return param2 = param1 + param2;
    }
  }
  console.log(add(2)(3));//5