Documentation for tx2.action doesn't match PM2 documentation

[joeskeen]

In the PM2 documentation it has an example of how to use tx2.action:

tx2.action('world', function(param, reply) {
  console.log(param)
  reply({success : param})
})

But this doesn't match any of the documented call signatures in the documentation for tx2:

tx2.action('run_query', (cb) => {
  cb({ success: true })
})
tx2.action('run_query', arg1, (cb) => {
  cb({ success: arg1 })
})

The TypeScript typings for this package, available in https://github.com/DefinitelyTyped/DefinitelyTyped/, only allow usage as documented:

    action(action_name: string, callback: (cb: (data: any) => void) => void): void;
    action<T extends object>(
        action_name: string,
        options: T,
        callback: (options: T, cb: (data: any) => void) => void,
    ): void;

(see https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/tx2/index.d.ts#L36)

Thus this TypeScript code is invalid, even though when I run it as JS it works.

tx2.action(job.name, (param, reply) => { reply(param) });

The documentation and typings need to be updated if this is a supported use-case as the PM2 docs would suggest.

CC @sasial-dev

[joeskeen]

My current workaround is thus:

type Tx2Action = (name: string, handler: (param: any, reply: (result: any) => void) => void) => void;

const action = tx2.action.bind(tx2) as Tx2Action;

action(job.name, (param, reply) => {
  reply(param);
});

Those are some pretty nasty typings though... way too many nested function types. Perhaps something like this would be better:

type ActionCallback = (result: any) => void;
type ActionHandlerNoParam = (reply: ActionCallback) => void;
type ActionHandlerWithParam = (param: string, reply: ActionCallback) => void;
type ActionHandler = ActionHandlerNoParam | ActionHandlerWithParam;

export type Tx2Action = (name: string, handler: ActionHandler) => void;

[joeskeen]

Also CC @zoernert - looks like your PR #7 may be related?