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An XMTP content type to support reactions to messages

Version published



Reaction content type

Status Status

This package provides an XMTP content type to support reactions to messages.

Open for feedback
You are welcome to provide feedback on this implementation by commenting on the Proposal for emoji reactions content type.

What’s a reaction?

A reaction is a quick and often emoji-based way to respond to a message. Reactions are usually limited to a predefined set of emojis or symbols provided by the messaging app.

Why reactions?

Providing message reactions in your app enables users to easily express a general sentiment or emotion toward a message. It also provides a handy way to acknowledge a message or show a particular emotional reaction without engaging in a detailed response.

Install the package

# npm
npm i @xmtp/content-type-reaction

# yarn
yarn add @xmtp/content-type-reaction

# pnpm
pnpm i @xmtp/content-type-reaction

Create a reaction

With XMTP, reactions are represented as objects with the following keys:

  • reference: The message ID for the message that is being reacted to
  • action: The action of the reaction (added or removed)
  • content: A string representation of a reaction (e.g. smile) to be interpreted by clients
const reaction: Reaction = {
  reference: someMessageID,
  action: "added",
  content: "smile",

Send a reaction

Now that you have a reaction, you can send it:

await conversation.messages.send(reaction, {
  contentType: ContentTypeReaction,

contentFallback text is provided by the codec and gives clients that don't support a content type the option to display some useful context. For cases where clients do support the content type, they can use the content fallback as alt text for accessibility purposes.

Receive a reaction

Now that you can send a reaction, you need a way to receive a reaction. For example:

// Assume `loadLastMessage` is a thing you have
const message: DecodedMessage = await loadLastMessage();

if (!message.contentType.sameAs(ContentTypeReaction)) {
  // We do not have a reaction. A topic for another blog post.

// We've got a reaction.
const reaction: Reaction = message.content;

Display the reaction

Generally, reactions should be interpreted as emoji. So, smile would translate to :smile: in UI clients. That being said, how you ultimately choose to render a reaction in your app is up to you.


Run yarn dev to build the content type and watch for changes, which will trigger a rebuild.


Before running unit tests, start the required Docker container at the root of this repository. For more info, see Running tests.

Useful commands

  • yarn build: Builds the content type
  • yarn clean: Removes node_modules, dist, and .turbo folders
  • yarn dev: Builds the content type and watches for changes, which will trigger a rebuild
  • yarn format: Runs prettier format and write changes
  • yarn format:check: Runs prettier format check
  • yarn lint: Runs ESLint
  • yarn test:setup: Starts a necessary docker container for testing
  • yarn test:teardown: Stops docker container for testing
  • yarn test: Runs all unit tests
  • yarn typecheck: Runs tsc



Package last updated on 13 Jun 2024

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