config.json

{
  "token": "Your Token Here",
  "prefix": "!"
}

FullBot02.js

//Require Discord.js
const Discord = require('discord.js')

//Require config.json
const config = require('./config.json')

//Create a new bot Account
const bot = new Discord.Client()

//Create a variable called responseObject containing responses for certain commands.
const responseObject = {
  'ayy': 'Lmao!',
  'coocla': 'Is the best person ever!',
  'potato': 'Tomato'
}

//Logging in with the bot Account using the config.json files
bot.login(config.token)

//When the bot is read, send a message to the console saying the bot is ready
bot.on('ready', () => {
  console.log('Bot is ready!')
})

//Whenever the bot detects a new message, this code will be ran
bot.on('message', (message) => {
  //Check if the content of the message objects starts with config.prefix
  if (message.content.startsWith(config.prefix)) {
    //Remove the prefix from the message content
    //Split it at every space and take the first word
    //Change the first word to lower case
    const command = message.content.substr(config.prefix.length).split(' ')[0].toLowerCase()

    //If the command variable is uqual to ping, succeed.
    if (command == 'ping') {
      //Send message containing the following text: Pong!
      message.channel.sendMessage('Pong!')
    }

    if (responseObject[command]) {
      message.channel.sendMessage(responseObject[command])
    }
  }
})