Canceling requests with TypeScript

[heruan]

Since the cancel/abort function is added runtime to the Promise<HttpResponseMessage> returned by .send() in http-client.js, the TypeScript compiler doesn't know about its existence.

[jods4]

I have a PR ready for this... except the build chain won't support it properly.

We need generics support to declare interface CancellablePromise<T> extends Promise<T>.
This is one of the latest change in babel-dts-generator but of course we can't use it because aurelia-http-client still uses Babel 5.8 but babel-dts-generator master is on 6.0 now.

[EisenbergEffect]

We hope to move to 6.x soon. We've been contributing to the dts generator a lot trying to get it updating to the new Babel version. I think we're really close. @cmichaelgraham can you comment on that?

[cmichaelgraham]

@jods4 babel-dts-generator has been updated to support generics. as part of this, it also has been updated to the new babel6 plugin architecture.

• Babel 6 Plugin Handbook
• Babel 6
• AST Explorer

the first aurelia repo to test against is metadata - a problem has been identified where class member's code comments were not being successfully included in the generated .d.ts file.

failing tests were created and the issues resolved, but during the code review, a refactoring was requested (a good suggestion).

i will try to get this added to the PR so we can proceed.

[EisenbergEffect]

@cmichaelgraham It looks like this is still a bug in the d.ts generator. Can you address it?

[cmichaelgraham]

i'll have a look 😄

[EisenbergEffect]

@cmichaelgraham Was this ever addressed?

[cmichaelgraham]

need to test with the latest... will do that tonight... (i think we should be ok with the required generics)

[cmichaelgraham]

@heruan - can you submit the PR so i can test with the latest babel-dts-generator?

ping @EisenbergEffect

[heruan]

@jods4 had a PR ready, let's hear from him!

[cmichaelgraham]

thanks @heruan 😄 @jods4 - can you submit a PR?

[jods4]

Hey guys, sorry that's so old now I'm really not sure where I made this anymore :D

BTW instead of inheritance, since then we got intersection types, so an alternative could be to type the function as Promise<T> & { abort(): void }

[michaelbull]

To piggyback on @jods4's comment, you can solve this problem in your own codebase by just declaring the following type:

type CancellablePromise<T> = Promise<T> & { cancel(): void }

I think this should be added more formally to the http-client type definitions though.

[jods4]

BTW, maybe that's worth opening another issue but whatwg has finally decided what is the standard way to abort a fetch. They said adding abort on Promise is not working well as soon as you chain them, so they opted for a different design based on a fetch controller. Maybe it's worth revising the design of http-client as well (of course abort could be left on the returned promise for back compat, but maybe not exposed in the .d.ts).

[michaelbull]

@jods4 do you have the link to the supporting documentation from whatwg? Would be useful going forward in this discussion, thanks.