Carbon/src/js/events/membership.js

const {Event} = require("./event")

function createMembershipEvent(membership, message) {
	return class extends Event {
		render() {
			super.render()
			return this.text(message(this.data))
		}

		static canRender(event) {
			return event.type == "m.room.member" && event.content.membership == membership
		}

	}
}
class UnknownMembership extends Event {
	render() {
		super.render()
		return this.text("Unsupported membership event")
	}

	static canRender(event) {
		return event.type == "m.room.member"
	}

}

const JoinedEvent = createMembershipEvent("join", () => "joined the room")
const InvitedEvent = createMembershipEvent("invite", (e) => `invited ${e.content.displayname} the room`)
const LeaveEvent = createMembershipEvent("leave", () => "left the room")

module.exports = [JoinedEvent, InvitedEvent, LeaveEvent, UnknownMembership]