functional programming - Currying function with unknown arguments in JavaScript

Question

In a recent interview, I was asked to write a function that adds numbers and accepts parameters like this:

add(1)(2)(3) // result is 6
add(1,2)(3,4)(5) // result is 15

The number of parameters is not fixed, and the arguments can be either passed in sets or individually.

How can I implement this add function?

Answer 1

Given your examples, the number of parameters is fixed in some ways.

As @ASDFGerte pointed out, your examples seem to return the result after three invocations. In this case a simple implementation without introducing terms like variadic and currying could be

function add(...args1){
  return function(...args2){
    return function(...args3){
      return args1.concat(args2).concat(args3).reduce((a,b)=>a+b)}}}
                
console.log(add(1)(2)(3))
console.log(add(1,2)(3,4)(5))