# Router

## [](#command) router.command()

Registers some middleware that will only be executed when the bot received a message that starts with the specifid command.

- **Type**

  ```ts
  interface Router {
    command(name: string, ...handlers: Handler[]): void;
  }
  ```

- **Details**

  The commands must meet the following criteria:
  - The command must start with a forward slash character (/).
  - The command must be composed of one or more uppercase or lowercase letters.
  - The letters in the command may be separated by one underscore (_).
  - The command must end with a single letter.

- **Example**

  The following route will match  `/hello`  command

   ```js
  bot.command('hello', () => {})
  ```

- **References**

  [`Handler`](#Handler)

## [](#hears) router.hears()

Registers some middleware(s) that will only be executed when the message contains some text specified by `pattern`

- **Type**

  ```ts
  interface Router {
    hears(pattern: Pattern, ...handlers: Handler[]): void;
  }
  ```

- **Example**

  This route will match butterfly and dragonfly, but not butterflyman, dragonflyman, and so on.

   ```js
  bot.hears(/.*fly$/, () => {})
  ```

- **References**

  [`Pattern`](#Pattern), [`Handler`](#Handler)

## [](#use) router.use()

Registers some middleware

- **Type**

  ```ts
  interface Router {
    use(...handlers: Handler[]): void;
  }
  ```

- **References**

  [`Handler`](#Handler)

## [](#Handler) Handler

- **Type**

  ```ts
  type Handler = (usr: User, tx: Transaction, next: NextFunction) => void;

  interface Transaction {}

  type NextFunction = (error: Error) => void;
  ```

- **References**

  [`User`](User.md#User)

## [](#Pattern) Pattern

- **Type**

  ```ts
  type Pattern = Pattern[] | RegExp | string;
  ```

- **References**

  [`Pattern`](#Pattern)