Guarding commands to whitelisted channels - workaround for discordjs/Commando#34

guards.js

/**
 * ./guards.js
 */

const store = require('./store.js');

exports.notAssigned = async function(msg, channel) {
  const assigned = await store.get(channel.id, false);

  return !assigned && msg.direct(`I am not assigned to ${channel}. Try another channel.`);
}

start.js

/**
 * ./commands/game/start.js
  */

const { Command } = require('discord.js-commando');

const { notAssigned } = require('../../guards.js');

module.exports = class StartCommand extends Command {
  constructor(client) {
    super(client, {
      name: 'start',
      memberName: 'start',
      group: 'game',
      description: `Starts new game round.`,
      guildOnly: true
    });
  }

  async run(msg) {
    const { channel } = msg;
    
    // Guard that restricts the command to whitelisted channels
    const g = await notAssigned(msg, channel); if (g) return g;
    
    msg.react('🎉');
    return msg.say(`**Round start!**`);
  }
};