matrix-bot-sdk

npm install matrix-bot-sdk

import {
    MatrixClient,
    SimpleFsStorageProvider,
    AutojoinRoomsMixin,
    RichReply,
} from "matrix-bot-sdk";

// where you would point a client to talk to a homeserver
const homeserverUrl = "https://matrix.org";

// see https://t2bot.io/docs/access_tokens
const accessToken = "YourSecretAccessToken";

// We'll want to make sure the bot doesn't have to do an initial sync every
// time it restarts, so we need to prepare a storage provider. Here we use
// a simple JSON database.
const storage = new SimpleFsStorageProvider("hello-bot.json");

// Now we can create the client and set it up to automatically join rooms.
const client = new MatrixClient(homeserverUrl, accessToken, storage);
AutojoinRoomsMixin.setupOnClient(client);

// We also want to make sure we can receive events - this is where we will
// handle our command.
client.on("room.message", handleCommand);

// Now that the client is all set up and the event handler is registered, start the
// client up. This will start it syncing.
client.start().then(() => console.log("Client started!"));

// This is our event handler for dealing with the `!hello` command.
async function handleCommand(roomId, event) {
    // Don't handle events that don't have contents (they were probably redacted)
    if (!event["content"]) return;

    // Don't handle non-text events
    if (event["content"]["msgtype"] !== "m.text") return;

    // We never send `m.text` messages so this isn't required, however this is
    // how you would filter out events sent by the bot itself.
    if (event["sender"] === await client.getUserId()) return;

    // Make sure that the event looks like a command we're expecting
    const body = event["content"]["body"];
    if (!body || !body.startsWith("!hello")) return;

    // If we've reached this point, we can safely execute the command. We'll
    // send a reply to the user's command saying "Hello World!".
    const replyBody = "Hello World!"; // we don't have any special styling to do.
    const reply = RichReply.createFor(roomId, event, replyBody, replyBody);
    reply["msgtype"] = "m.notice";
    client.sendMessage(roomId, reply);
}