xiao/commands/info/id.js

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

module.exports = class IDCommand extends Command {
	constructor(client) {
		super(client, {
			name: 'id',
			aliases: ['user-id', 'member-id'],
			group: 'info',
			memberName: 'id',
			description: 'Responds with a user\'s ID.',
			args: [
				{
					key: 'user',
					prompt: 'Which user do you want to get the ID of?',
					type: 'user',
					default: msg => msg.author
				}
			]
		});
	}

	run(msg, { user }) {
		return msg.say(`${user.username}'s ID is ${user.id}.`);
	}
};