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

This is concept of currying in JS.
Solution for your question is:

function add(a) {
  return function(b) {
    return a + b;
  };
}

This can be also achieved using arrow function:

let add = a => b => a + b;

solution for add(1)(2)(5)(4)........(n)(); Using Recursion

function add(a) {
  return function(b){
    return b ? add(a + b) : a;
  }
}

Using ES6 Arrow function Syntax:

let add = a => b => b ? add(a + b) : a;