How does return works in JavaScript

Question

I have one simple recursive function which adds all it's previous numbers.

function add(n) {
  if (n == 0) {
    return 1; // when it reaches here it should give me 1.
  }
  return n + add(n - 1);
}

console.log( add(5) ); // give me 16

when the execution reaches line number 3, it should return me 1, but it is return me 16. how return is actually working here ?

Thakur Karthik · Accepted Answer · 2019-09-22 04:05:32Z

3

Recursion pauses the program at recursion step call and continue solving the sub problem and when a base condition is hit all the return statements pass the control back to the callee statement.

So

add(5)-->return 5+add(4)
                     |-->return 4+add(3)
                                   |-->return 3+add(2)
                                                 |-->return 2+add(1)
                                                                 |-->return 1+add(0)//base condition, return 1 for add(0) which in return return 2

1-->2-->4-->7-->11-->16 (In reverse)

answered Sep 22, 2019 at 4:05

Thakur Karthik

3,6483 gold badges17 silver badges27 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

jsduniya Over a year ago

this happens only in recusrive case ?

Thakur Karthik Over a year ago

Yes recursion works in this way.You may follow this link for some basic understanding. freecodecamp.org/news/…

C Miller Over a year ago

You may be thinking of it like you would a while loop that can exit with a return statement. Instead of recursion which returns it back to the calling function which returns that back to its calling function, and so on. At least that was the problem for me when I started recursions.

fisayo-dmg · Accepted Answer · 2019-09-22 04:08:53Z

3

that is because the conditional statement that your line 3 is in says to return 1 only if the argument n passed in is equals to 0. The function you are calling at the end of the code is passing in an argument of 5.

the first return statement would only work if condition in the if statement is true, otherwise it goes to the second return which calls the function again within itself.

answered Sep 22, 2019 at 4:08

fisayo-dmg

412 bronze badges

Collectives™ on Stack Overflow

How does return works in JavaScript

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related