What is the meaning of returning a function from another function?

Question

What is the meaning of returning a function from another function in javascript. Is this is same as if I call a function which is in another function

function fun(c){
    let a=3;
     return function(){
        return a+c;
    }
}
let add=fun(2);
console.log(add);

. And my second question is why this add variable is a function.

You added the `closure` tag, so you do know what's going on? — georg, May 13 '21 at 08:27
"*What is the meaning of returning a function*" basically answers "*why this add variable is a function*". — VLAZ, May 13 '21 at 08:31
@georg yeah..inner function preserving the value of a and c which is the concept of closure — Ishan Ahmed, May 13 '21 at 08:58

score 1 · Accepted Answer · answered May 13 '21 at 08:29

1

Currently, the object which you are returning is the function. In this context, variable add contains a reference to the function which you have to invoke.

answered May 13 '21 at 08:29

Łukasz Ozimek

108
5

score 1 · Answer 2 · answered May 13 '21 at 08:29

This is called currying. It allows you to apply arguments to functions one by one. Example:

const add = a => b => a + b // Function that takes `a` and returns a function that adds `a` to `b`
const addThree = add(3) // bind `a` to 3. This is a function that takes `b` and adds 3 to it
console.log(addThree(1)) // now `b` is 1, it's gonna be added to `a` and return the final value

There's a lot of literature about currying and partial application. Google is your friend

What is the meaning of returning a function from another function?

2 Answers2