element-web/src/autocomplete/RoomProvider.js

import AutocompleteProvider from './AutocompleteProvider';
import Q from 'q';
import MatrixClientPeg from '../MatrixClientPeg';
import Fuse from 'fuse.js';

const ROOM_REGEX = /(?=#)([^\s]*)/g;

let instance = null;

export default class RoomProvider extends AutocompleteProvider {
    constructor() {
        super();
        this.fuse = new Fuse([], {
           keys: ['name', 'roomId', 'aliases']
        });
    }

    getCompletions(query: String) {
        let client = MatrixClientPeg.get();
        let completions = [];
        const matches = query.match(ROOM_REGEX);
        const command = matches && matches[0];
        if(command) {
            // the only reason we need to do this is because Fuse only matches on properties
            this.fuse.set(client.getRooms().filter(room => !!room).map(room => {
                return {
                    name: room.name,
                    roomId: room.roomId,
                    aliases: room.getAliases()
                };
            }));
            completions = this.fuse.search(command).map(room => {
                return {
                    title: room.name,
                    subtitle: room.roomId
                };
            }).slice(0, 4);;
        }
        return Q.when(completions);
    }

    getName() {
        return 'Rooms';
    }
    
    static getInstance() {
        if(instance == null)
            instance = new RoomProvider();
        
        return instance;
    }
}