How can I get the type of a variable that is wrapped in a Maybe type?

In this case, the implementation of Maybe is:

type Maybe<T> = T | null

Let's assume I have a data that are typed like that:

type MyData = { postTitle: string } & { meta: Maybe<{ tags: Array<El> }> }

I need to pluck the type of El to use it elsewhere.

I'm a TS noob. I've realize that it's pretty easy to get any nested type if it is not wrapped, like type Easy= Simple['one']['heyAnArrayHere'][number]['propOfArrayElement'] but once Maybe comes in a way, I am done.

I think that I need a conditional type, possibly something like type Expand<T> = T extends Maybe<infer U> ? U : T, but that doesn't work at all.

Any help would be appreciated!

CodePudding user response：

You are looking for the NonNullable<Type> utility:

TS Playground link

type El = HTMLElement;
type Maybe<T> = T | null;
type MyData = { postTitle: string } & { meta: Maybe<{ tags: Array<El> }> }

type AlsoEl = NonNullable<MyData['meta']>['tags'][number];