Update Node event handler to support multiple events

[brendantruleo]

No description provided.

[burrows]

This is great, but I think it would be a slightly nicer API to pass the event types as variadic arguments instead of as an array of types. Having the handler as the last arg makes this a little tricky, but it is possible to do as of typescript 4.0:

  on<T extends E['type']>(
    ...args: [T, ...T[], EventHandler<C, E, T> | string | string[]]
  ): this {
    const types = args.slice(0, -1) as T[];
    const handler = args[args.length - 1] as
      | EventHandler<C, E, T>
      | string
      | string[];

    for (const type of types) {
      this.handlers[type] =
        typeof handler === 'string' || Array.isArray(handler)
          ? () => ({ goto: handler })
          : handler;
    }

    return this;
  }

This allows you to do this:

s.on('FOO', 'BAR', BAZ', (ctx, evt) => {});

instead of this:

s.on(['FOO', 'BAR', BAZ'], (ctx, evt) => {});

This also has the added benefit of preventing an empty list of event types, which the array approach would not catch.

This issue led me to the solution above.

[brendantruleo]

@burrows Cool I didn't know about variadic tuple typing and I agree I like that API better. Updated here b217818.