re-export-an-imported-type.md

Re-Export An Imported Type

I have a TypeScript module that is defining an XState machine. Among other things, it imports the DoneEventObject type from xstate. I want to re-export that type so that any modules using this machine have access to that type definition.

This can be done a couple of ways. One way to import it under an aliased name and then assign + export it using the original name.

import {Machine, DoneEventObject as _DoneEventObject} from 'xstate'

export type DoneEventObject = _DoneEventObject

This works, but adds some potential indirection and confusion through the double assignment.

Another way of doing this is to reference the type off the import statement as part of an assignment.

import {Machine} from 'xstate'

export type DoneEventObject = import('xstate').DoneEventObject

This imports, assigns, and exports the type in a single statement.

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