DEV Community

Advanced TypeScript Exercises - Question 10

Pragmatic Maciej on October 23, 2020

Intersection type level operator & has changed in the last versions of TypeScript. The current behavior escalates 'never' type, so if any of fi...

Read full post

Stepan Zubashev • Oct 23 '20

My solution: bit.ly/35ojBlc
code:

type Merge<A, B> = & Omit<A, keyof B> & Omit<B, keyof A> & { [key in keyof A & keyof B]: (A[key] & B[key]) extends never ? A[key] : A[key] & B[key] };

I hope I understand the task properly. Unfortunately my solution doesn't show anything except "XY" when you hover it. But it looks like it passes the test.

Stepan Zubashev • Oct 23 '20

in such a way that the latter type will overwrite types of fields of former type.

I didn't read it properly. But, BTW, my task is more interesting :)
My code really merges 2 objects. But it avoids "never" during merge. When there's never it takes the 2nd arguments value.