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Comment by jitl | Hacker News Reader

Note that the decorators standard has changed substantially, and the experimental decorators implementation in Typescript now varies greatly from the existing proposals. The current feature has not been updated in years. I would not use this feature in my code, especially for critical facilities, or build a framework around it.

For what it’s worth, it seems like the proposal may move towards stage 3 soon - another round of review is going on here: https://github.com/tc39/proposal-decorators/issues/442

So, beware libraries or frameworks that rely on this toolset.

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Just today i was bitten by a bug in a framework called NestJS that makes heavy use of decorators: Certain decorator they define doesnt work with Jest test framework.

Sounds like you were bitten by Jest inadequacies, no?

Jest is inadequate because it doesn't support some non-standard experimental feature that was shoehorned into TypesScript to make it look more like C#?

This is a JavaScript feature and confusing the two makes finding answers to Typescript questions much harder.

But yes, I think jest, a "JavaScript testing framework designed to ensure correctness of any JavaScript codebase" should support JavaScript features, even the ones you don't like the provenance of.

But decorators aren't a JavaScript feature, that's the point of this comment thread.

Some form of them might eventually be a JavaScript feature, but anything using them now is potentially incompatible with that future form.

Oh yeah, sorry, I shouldn't have worded it that way. the decorators are being transpiled at runtime to standard JS, so why shouldn't tooling like jest be able to work with that?

Because there is something wrong happening while the transpilation of the non-standard feature is happening.

I use NestJS with Jest just fine. Lots of decorators, too. What bug did you encounter?

It’s truly insane to me that we’re still waiting on decorators from TC39. I’ve been seeing warnings to not use them SINCE shortly after ES2015. Since you’ve been able to use them for 7 years via transpilers, I wouldn’t hold my breathe on TC39 finally ending their bike shedding anytime soon. Feels like if the feature is useful to you, you should use it. If something changes, it would be an easy thing to codemod.

Yea, it makes me really worried about Angular's future updates given its heavy usage of decorators.

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