await message discord.js
message.channel.awaitMessages(m => m.author.id == message.author.id,
{max: 1, time: 30000}).then(collected => {
// only accept messages by the user who sent the command
// accept only 1 message, and return the promise after 30000ms = 30s
// first (and, in this case, only) message of the collection
if (collected.first().content.toLowerCase() == 'yes') {
message.reply('Shutting down...');
client.destroy();
}
else
message.reply('Operation canceled.');
}).catch(() => {
message.reply('No answer after 30 seconds, operation canceled.');
});