discord.js wait before send message

Question

My problem is that I want my discordbot wait during the giveaway until the giveway is out

Here's my code :

        const Discord = require('discord.js');
        const client = new Discord.Client();
        const config = require("./config.json");
        var prefix = config.prefix;
        client.login(config.token);

    client.on('ready',() => {
        console.log('I\'m online');
    })

    client.on('message', message => {

      const args = message.content.slice(prefix.length).trim().split(/ +/g);
      const command = args.shift().toLowerCase();


      if (command === 'gstart') {
        var channel = args[0].slice(2).slice(0, -1);
        var price = args[1];
        var End = args[2];
        var EndMS = End*1000;
        client.channels.get(channel).send({embed: {
            color: 3447003,
            author: {
              name: '',
              icon_url: ''
            },
            title: "",
            url: "",
            description: "",
            fields: [{
                name: 'a Giveaway just started !',
                value: 'Put\'🎉\' in react of this message to try to win \'' + price + '\'.'
          },     
        ],
        timestamp: '',
        footer: {
          icon_url: '',
          text: 'End in ' + End + ' secondes !'
        }
      }
    })
    .then(msg => {
      msg.react('🎉');
      client.channels.get(channel).send('STUFF')(EndMS); // my problem is here
    })
  }

He must wait EndMS milis and, after, choose a winner but for now, he send instantly STUFF, for choosing the winner, I will not ask it for you. All I want is he wait before sending Stuff.

Thanks you for helping me.

Solution

Well it depends. If you trust on the bot's uptime (if the bot wont ever crash or restart during a giveaway) you can use a setTimeout:

setTimeout(function(){ 
    doSomething(); 
}, 3000);

This will run doSomething() after 3 seconds (3000 milliseconds).
So what you need to basically do is:

.then(msg => {
  msg.react('🎉');
  setTimeout(function(){
     client.channels.get(channel).send("It's finished!");
  }, EndMS);
})

Note: You might have to tweak the EndMS part.