Search⌘ K
Home
Courses
The JavaScript Interview Handbook: 100+ Interview Questions

Solution Review: Let's Curry!

Learn how to convert any JavaScript function into a curried version by understanding recursive argument handling. This lesson walks you through implementing currying that collects arguments until complete, then executes the original function, enhancing your functional programming skills.

We'll cover the following...

Solution #

Javascript (babel-node)
function currying(func) {
    function curriedfunc(...args) {
        if(args.length >= func.length) {
            return func(...args);
        } else {
            return function(...next) {
                return curriedfunc(...args,...next);
            }
        }
    }
    return curriedfunc;
}
function multiply(a, b, c) {
    return a*b*c;
}
let curried = currying(multiply);
console.log(curried(2)(3)(4))
console.log(curried(2,3)(4))
console.log(curried(2,3,4))
console.log(curried(5)(6,7))

Explanation #

A simple approach for converting the multiply function to a curried function is:

Javascript (babel-node)
function multiply(a){
    return function(b){
      return function(c){
        return a*b*c
      }
  }
  
}
console.log(multiply(2)(3)(4))

However, the question requires you to write a function, currying, that takes any function and converts it into a currying function. So how do we do that?

  • First, we are passing the function, func, to our function, currying (line 1).

    function currying(func)

  • The next step is to think about the output. Re-stating the problem, we want to return a currying function. Hence, we define the function ...