Return object from a recursive function that rearranges array of literal objects

Question

I have a function that takes a literal object as an input. as an outcome it should return 2 arrays of objects.

It is a recursive function so the return happens at n-th recursion cycle with the following data:

//code
const filterObject = (object, array1 = null, array2 = null) => {
let a1 = array1 === null?[]: array1; //array1 is passed as a part of recursion and when recursed is not null
let a2 = array2 === null?[]: array2; //same here
...
//some filtering and object manipulation to create **composedObject**
...
if (condition x is met){
a1.push(composedObject)
}
if( condition y is met ){
a2.push(composedObject)
...
//filtering out parts of initial object that were used
//what is left is assembled into **untreatedObject**
...
if (there are still parts of the initial object that are left untreated){
 filterObject(untreatedObject, a1, a2); //here recursion happens and we pass these arrays there as well as they will continue to be populated
}
else if (everything is filtered and objects are ready){
console.log(a1) //values are present and correct
console.log(a2) //values are present and correct
 return { a: a1, b: a2};
}

/*
  where

   array1:[
   {
    a: 1,
    b: 'skdfhkdj',
    c:[
     {
       index:0,
       code :'red'
     },
     {
       index:1,
       code :'redcwrg'
     }
    ]
   }
  ],
  
 array2:[
   {
    a: 1,
    b: 'skdfhkdj',
    c:[
     {
       index:2,
       code :'redaxac'
     },
     {
       index:3,
       code :'reddd'
     }
    ]
   }
  ]
*/

const result = filterObject(object, null,null);
console.log(result); //**gives undefined**.

QUESTION When i try to call this function const result = filterObject(object, null,null) (null,null here is the starting values for the arrays. they are assigned to [] in the beginning of the function and then when recursion happens they are sent too so that new arrays can be upserted)

and when i log it, the result is of type "undefined" and i am positive that the function does have the objects in array before return happens

So where can I be wrong?

Thanks in advance

You should be asking only one question, otherwise this will be closed as being too broad. — trincot, Oct 21 '21 at 10:07
Your second question is [covered here](https://stackoverflow.com/questions/14220321/how-to-return-the-response-from-an-asynchronous-call) — Liam, Oct 21 '21 at 10:08
If you are going to stick with the first question (and remove the second one), then please add your code with which we can reproduce the problem. — trincot, Oct 21 '21 at 10:08
This looks more like pseudo code, but one import thing is missing: your code does not *return* the object returned from a recursive call. Add `return`. — trincot, Oct 21 '21 at 10:44
@trincot I'm sorry I am a little confused here.. I have literally the `return { a: a1, b: a2};` is it not enough ? and i can't provide the real code because you know ..i'll get fired :) — RomanSmoll, Oct 21 '21 at 10:46
That is not the return value from the recursive call. That is the base case. Your code doesn't do the return of the other, recursive case. So to put it clear, you need `return filterObject(untreatedObject, a1, a2);` — trincot, Oct 21 '21 at 10:47
@trincot HOW Do I mark your comment as a solution so that you get some points ??? Man thank you so so so much ! I got it ..so In the condition that there is a recursion to be made we return the recursion.. and if there is nothing to recurse left , we simply return the object as i did. Very , VERY much obliged ! all the energy and love to you m8 — RomanSmoll, Oct 21 '21 at 10:55

score 1 · Accepted Answer · answered Oct 21 '21 at 10:58

One import thing is missing: your code does not return the object returned from a recursive call. It only has a return for the base case. Your code doesn't perform the return of the other, recursive case.

So to put it clear, you need

return filterObject(untreatedObject, a1, a2);

Return object from a recursive function that rearranges array of literal objects

1 Answers1