Merge non-existing fields

[hriiss]

I am wondering if this is possible, as I haven't seen it in the docs.
I want to merge 2 objects y1 and y2.
If I do:
deepmerge(y1, y2)
and y2 has some fields that don't exist in y1, it wont override or add them at all.
I am wondering if it's possible to change this.
Thank you.

[RebeccaStevens]

The result of the merge should have all the fields of y1 and y2.
If you want y1 to be modified to have the fields of y2, you need to use deepmergeInto

const x = deepmerge(y1, y2);

https://codesandbox.io/p/sandbox/deepmerge-ts-example-forked-nx5sp7

deepmergeInto(y1, y2);

https://codesandbox.io/p/sandbox/deepmerge-ts-example-forked-t9y227

[hriiss]

The result of the merge should have all the fields of y1 and y2. If you want y1 to be modified to have the fields of y2, you need to use deepmergeInto

const x = deepmerge(y1, y2);

https://codesandbox.io/p/sandbox/deepmerge-ts-example-forked-nx5sp7

deepmergeInto(y1, y2);

https://codesandbox.io/p/sandbox/deepmerge-ts-example-forked-t9y227

If I merge y1 and y2, I want to overwrite the fields in y1 with the existing fields of y2.
Any other field that doesn't exist should be added from y1.
Is this somehow possible?

Example:

const y1 = {
  field1: "value1",
  field2: {
    a: 0,
    b: 1
  }
}

const y2 = {
  field1: "newvalue",
  field3: "newvalue2"
}

const newObject = deepmerge(y1, y2);

Output:
{
  field1: "newvalue",
  field2: {
    a: 0,
    b: 1
  },
  field3: "newvalue2"
}

[RebeccaStevens]

That's exactly how it works:

https://codesandbox.io/p/sandbox/deepmerge-ts-example-forked-nx5sp7

[hriiss]

That's exactly how it works:

https://codesandbox.io/p/sandbox/deepmerge-ts-example-forked-nx5sp7

Thank you for showing me an example.
It seems like there was an error on my side with how I fetched the object I wanted to merge into.