Implement a @nonnull JSDoc tag

[Daniel Rosenwasser (DanielRosenwasser)]

Fixes#23405.

[TypeScript Bot (typescript-bot)]

Looks like you're introducing a change to the public API surface area. If this includes breaking changes, please document them on our wiki's API Breaking Changes page.

Also, please make sure Daniel Rosenwasser (@DanielRosenwasser) and Ryan Cavanaugh (@RyanCavanaugh) are aware of the changes, just as a heads up.

[NemoStein (NemoStein)]

TS 5.5 beta is released, but this isn't merged yet... Are there any plans to ship this with 5.5 or will it be pushd forward?

[Andrey (codenomnom)]

Any news on this one? It's been a while...

[Tatsunori Uchino (tats-u)]

Nathan Shively-Sanders (@sandersn) You should leave a review to other members if you are too busy to review it.
About 1 year has been passed.

[aweebit]

@nonnull is a pretty bad name for this, makes it feel like it's only about null, and not undefined.

@nonnullable is better as it corresponds to the NonNullable utility type's name.

@nonnullish with nullish as in the nullish coalescing operator meaning exactly that, the null and undefined values, is also a good alternative.

But my favorite option is actually /** @type {!} */.

[Bart Louwers (louwers)]

I like nonnullable better, it is a bit more verbose, but JSDoc does not shy away from some verbosity.

[TypeScript Bot (typescript-bot)]

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