Typescript: Spread types may only be created from object types

This is fixed in TypeScript Version 3.2. See Release Notes.

Looks like spread with a generic type isnt supported yet, but there is a GitHub issue about it: Microsoft/TypeScript#10727.

For now you can either use type assertion like @Jevgeni commented:

function foo<T extends object>(t: T): T {n  return { ...(t as object) } as T;n}n

or you can use Object.assign which has proper type definitions.

function foo<T extends object>(t: T): T {n  return Object.assign({}, t);n}n

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You can use blank curly brackets {} or an interface like below examples:

goodsArray.map(good => {n  return {n    id: good.payload.doc.id,n    ...good.payload.doc.data() as {}n  };n});n

goodsArray.map(good => {n  return {n    id: good.payload.doc.id,n    ...good.payload.doc.data() as Goods // Goods is my interface namen  };n});n

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Version 3.2 of Typescript fixed this. The two PRs that improve handling of spread and rest parameters are:

You can try it out now using npm install [email protected].

With 3.2 your code works as is.

Version 3.2 has been released on November 29th, 2018, you can read more about it here.

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