How to Create, Register, and Handle a Slash Command in Discord.js v14

Desired Outcome

Deploy a single slash command that appears instantly in a guild, registers correctly with Discord’s REST API, and responds to user interactions with a simple message.

Prerequisites

• Node.js 16.9.0 or newer (recommended 18.x LTS).
• discord.js v14 installed via npm.
• A bot token with the applications.commands permission.
• Valid guild ID for immediate testing (global commands take up to an hour).
• Environment variables or a .env file storing DISCORD_TOKEN and GUILD_ID.

Step‑by‑Step Procedure

1. Create the Command JSON

// commands/ping.js
module.exports = {
  name: 'ping',
  description: 'Replies with Pong!',
  // Optional: add options here
};

2. Bulk‑Register the Command

// register.js
require('dotenv').config();
const { REST } = require('@discordjs/rest');
const { Routes } = require('discord-api-types/v10');
const fs = require('fs');

const token = process.env.DISCORD_TOKEN;
const clientId = process.env.CLIENT_ID; // from Developer Portal
const guildId = process.env.GUILD_ID;

const commandFiles = fs.readdirSync('./commands').filter(file => file.endsWith('.js'));
const commands = commandFiles.map(file => require(`./commands/${file}`));

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

(async () => {
  try {
    console.log('Started refreshing application (/) commands.');
    await rest.put(
      Routes.applicationGuildCommands(clientId, guildId),
      { body: commands }
    );
    console.log('Successfully reloaded application (/) commands.');
  } catch (error) {
    console.error(error);
  }
})();

Run node register.js from the project root. The command should appear immediately in the guild chat.

3. Handle the Interaction in the Bot

// bot.js
require('dotenv').config();
const { Client, GatewayIntentBits } = require('discord.js');
const client = new Client({ intents: [GatewayIntentBits.Guilds] });

client.once('ready', () => {
  console.log(`Logged in as ${client.user.tag}`);
});

client.on('interactionCreate', async interaction => {
  if (!interaction.isChatInputCommand()) return;

  if (interaction.commandName === 'ping') {
    await interaction.reply('Pong!');
  }
});

client.login(process.env.DISCORD_TOKEN);

Start the bot with node bot.js. Type /ping in the guild and you should see a reply.

Expected Checks

• In the Developer Portal, the command appears under the Guilds > Guild Name > Commands tab.
• In Discord, typing / shows ping in the autocomplete list.
• The bot’s console logs the interactionCreate event with commandName: ping.
• When you invoke /ping, the bot replies with Pong!.

Recovery & Troubleshooting

• Command not showing up? Verify CLIENT_ID and GUILD_ID are correct. Re‑run node register.js and check for errors.
• Rate‑limit 429 error? Bulk register fewer than 200 commands or space out requests.
• Bot cannot register? Ensure the bot has the applications.commands permission in the target guild.
• Interaction handler not triggered? Confirm the bot is connected to the same guild and that the command name matches exactly.
• Use client.application.commands.fetch() in a script to programmatically confirm the command exists on Discord’s side.

Limitations

• Global commands (registered via Routes.applicationCommands) can take up to an hour to propagate; use guild commands for quick iteration.
• Discord’s API may change; keep @discordjs/rest and discord-api-types up to date.
• Storing tokens in plain text is insecure; use environment variables or secret management services.

Practical Verification

After registration, run:

curl -H "Authorization: Bot <token>" \
  https://discord.com/api/v10/applications/<appId>/guilds/<guildId>/commands

Inspect the JSON response for your command’s name and description to confirm successful registration.