app.message payload arg compatibility in TypeScript

The message argument in app.message listeners does not provide sufficient properties in TypeScript.

Property ‘user’ does not exist on type ‘KnownEventFromType<“message”>’. Property ‘user’ does not exist on type ‘MessageChangedEvent’.ts(2339)

A workaround is to cast the message value by (message as GenericMessageEvent).user but needless to say, this is not great.

---

I ran into this today also. Trying to use the official example from https://slack.dev/bolt-js/concepts

// This will match any message that contains 👋
app.message(':wave:', async ({ message, say }) => {
  await say(`Hello, <@${message.user}>`);
});

and immediately getting a ts compile error. This is not a great first-time experience. Not even sure how to get it working.

_Originally posted by @memark in https://github.com/slackapi/bolt-js/issues/826#issuecomment-830565064_

[maksimf]

It’s a pity to see that after a year since this issue has been created we still don’t have a ts support of the very basic example in the README 😕

[verveguy]

My advice: don’t bother trying to use Bolt with Typescript at this point. Perhaps one day slack will genuinely prioritize Typescript.