Advanced TypeScript Exercises - Question 10

Intersection type level operator & has changed in the last versions of TypeScript. The current behavior escalates 'never' type, so if any of fields will produce empty/never type, the whole composite will end as 'never'. Let's see some examples:

type X  = {    a: 1    b: number}type Y = {    a: 2    b: string    c: boolean}// XY is never, as field 'a' evaluates as 1 & 2 which is nevertype XY = X & Y 

More about this TS behavior you can find here:

• No empty intersections
• Reduce intersections by discriminants

Exercise will be about having different intersection behavior. Our task is to write Merge type level function which will merge two product/object types. Our final Merge should be able to create a type from above X and Y in such a way that the latter type will overwrite types of fields of former type.

type XY = Merge<X,Y>// XY should be {a: 2, b: string, c: boolean}

Link to the playground with the task.

Good luck! If you have a solution then don't hesitate to link it in the comment. Answer will be published soon!

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