LazyBot/app/slash_commands.js

const { REST, Routes } = require('discord.js');

module.exports = async () => {
  const TOKEN = process.env.BOT_TOKEN;
  const CLIENT_ID = process.env.CLIENT_ID;

  const commands = [
    {
      name: 'ping',
      description: 'Replies with Pong!',
    },
  ];

  const rest = new REST({ version: '10' }).setToken(TOKEN);

  try {
    console.log('Started refreshing application (/) commands.');

    await rest.put(
      Routes.applicationCommands(CLIENT_ID),
      { body: commands }
    );

    console.log('Successfully reloaded application (/) commands.');
  } catch (error) {
    console.error(error);
  }
};