Typescript connection.once inconsistency

[lopezbertoni]

Hi,

Using ably js v 1.1.18

When I want to use the Promise based API and found that in the connection.once method the compiler doesn't distinguish between the Callback based and the Promise based.

const connectedPromise = this.ablyClient.connection.once('connected'); connectedPromise.then(x => console.log('Hey'));

The error is: Property 'then' does not exist on type 'void'

The workaround is to do add a casting to any:

const connectedPromise: any = this.ablyClient.connection.once('connected'); connectedPromise.then(x => console.log('Hey'));

Looking at ably.d.ts

once(eventOrCallback: EventType | CallbackType, callback?: CallbackType): void; once(event: EventType): Promise<ResultType>;

There's really no way to tell the difference between the two methods since the callback in the first one is optional.

[SimonWoolf]

Fair comment. Mind trying the typings in #610 and letting me know if that fixes your issue?

[lopezbertoni]

@SimonWoolf Thanks for the quick update.
Just tried the typings in #610 and they worked like a charm.

Thanks!

[SimonWoolf]

Typings fix released in 1.1.19; apologies for the delay

[lopezbertoni]

Thanks!