include "typings" field in package.json

[rolandjitsu]

Now that the TS compiler supports module resolution via node, it would be nice not to use TSD to install the typing but instead have them included with the npm package.

[dougwilson]

We don't have any typings. What would we put in the field?

[blakeembrey]

@dougwilson I would be interested in maintaining them, if that sounds reasonable.

Edit: I'll be working on some related type testing tools in https://github.com/typings/typings which will complement any such support for typings.

[dougwilson]

@blakeembrey , that is absolutely reasonable! I was just talking about these typings today and I think Express should provide official typings for TypeScript as a feature! This means that we would be invested in properly maintaining them as part of the normal commit and release process. If you want to provide the initial typings for Express, that would be amazing!

Ideally I would love it if we could achieve these things:

1. Provide bindings to users of Express
2. Add a step to our CI that would validate that the bindings are correct somehow (to help prevent them from deteriorating accidentally)

These can be independent tasks, but I think Express is going to say yes to supporting TypeScript binding out of the box.

[blakeembrey]

Fantastic, I'll work on making sure the CI step is solved properly this week.

[rolandjitsu]

@blakeembrey that sounds great 👍 @dougwilson does this mean that typings will also be added to the other expressjs packages (morgan, session, etc.)?

[dougwilson]

does this mean that typings will also be added to the other expressjs packages (morgan, session, etc.)?

yes

[rolandjitsu]

Great, because I was having a hard time figuring out how to write those typings properly as I kept getting some errors about the way I was declaring them (I was using ambient typings and I realized that is not the way to go).

[LinusU]

We actually had this problem come up in multer where the type file that someone used wouldn't account for our middleware adding fields to the req object (namely req.file). Is this a problem that could be solved somehow? I think that it affects most middleware...

Other than that, we would be happy to include and maintain "typings" for multer as well :)

[blakeembrey]

@LinusU Mutations are hard to represent in TypeScript, especially with things like adding a field during middleware execution. It's possible to merge the interfaces and we should do that, if nothing else, but I'm not aware of a way to declaratively merge types depending on possible in middleware. That's something I've been thinking about anyway, but I'm glad to share an example of how this would work.

The reason I haven't yet tried to merge this into Express is because I haven't had time to solve the test suite involved. The closest I have is a feature I've had for a while - bundle the typings, then run the TypeScript compiler, then run unit tests as usual.

[jeffbcross]

Would maintainers be interested in converting the express source to TypeScript, so we could automatically generate correct typings with each release? I'd be down for helping with the conversion. // @dougwilson @ritch