Listening to messages

To listen to messages that your app has access to receive, you can use the message() method which filters out events that aren’t of type message .A message() listener is equivalent to event('message')

The message() listener accepts an optional pattern parameter of type string or RegExp object which filters out any messages that don’t match the pattern.

// This will match any message that contains 👋
app.message(':wave:', async ({ message, say }) => {
  // Handle only newly posted messages here
  if (message.subtype === undefined
    || message.subtype === 'bot_message'
    || message.subtype === 'file_share'
    || message.subtype === 'thread_broadcast') {
    await say(`Hello, <@${message.user}>`);
  }
});

Using a RegExp pattern

A RegExp pattern can be used instead of a string for more granular matching.

All of the results of the RegExp match will be in context.matches.

app.message(/^(hi|hello|hey).*/, async ({ context, say }) => {
  // RegExp matches are inside of context.matches
  const greeting = context.matches[0];

  await say(`${greeting}, how are you?`);
});

Filtering on event subtypes

You can filter on subtypes of events by using the built-in subtype() middleware. Common message subtypes like message_changed and message_replied can be found on the message event page.

// Import subtype from the package
const { App, subtype } = require('@slack/bolt');

// Matches all message changes from users
app.message(subtype('message_changed'), ({ event, logger }) => {
  // This if statement is required in TypeScript code
  if (event.subtype === 'message_changed'
    && !event.message.subtype
    && !event.previous_message.subtype) {
    logger.info(`The user ${event.message.user} changed their message from ${event.previous_message.text} to ${event.message.text}`);
  }
});