Chat Events and Commands

Responding to messages, adding custom commands

#Chat Events

#Chat Event

The chat event fires when a player send a message in chat. It's mostly used to cancel messages from being sent.
Here's an example which replies with "Aw man" when a player says "creeper" (ignoring case). => {
  // Check if message equals creeper, ignoring case
  if (event.message.trim().toLowerCase() == 'creeper') {
    // Schedule task in 1 tick, because if you reply immediately, it will print before player's message
    event.server.scheduleInTicks(1, event.server, ctx => {
      // Tell everyone "Aw man", colored green. Callback data is the server'Aw man'))
Here's an example of cancelling the event. => {
  // Check if message starts with "!some_command"
  if (event.message.startsWith('!some_command')) {
    // Reply to the player and cancel the event

#Decorate Chat Event

The decorate chat event also fires when a player sents a message, however it's used to modify its content.
The event is not cancellable.
This event only exists on 1.19.2 and above! Use the normal chat event for this if you're on 1.18 and below!
Here's an example, which removes the letter "g" from players' messages
PlayerEvents.decorateChat(event => {
  // Remove the letter "g"
  event.setMessage(event.message.replace('g', ''))
Here's another example, this time replacing :sword: with the sword emoji
PlayerEvents.decorateChat(event => {
  // Replace `:sword:` with the sword emoji
  event.setMessage(event.message.replace(':sword:', '⚔'))

#Command Events

#Command Event

The command event is an event which is fired when a command is ran. It's cancellable.

#Command Registry Event

The command registry event can be used to register custom commands. It's not cancellable.
Here's an example of a simple /fly command.
ServerEvents.commandRegistry(event => {
  const { commands: Commands, arguments: Arguments } = event
  event.register(Commands.literal('fly') // The name of the command
    .requires(s => s.hasPermission(2)) // Check if the player has operator privileges
    .executes(c => fly(c.source.player)) // Toggle flight for the player that ran the command if the `target` argument isn't included
    .then(Commands.argument('target', Arguments.PLAYER.create(event))
      .executes(c => fly(Arguments.PLAYER.getResult(c, 'target'))) // Toggle flight for the player included in the `target` argument
  // Helper function
  let fly = (player) => {
    if (player.abilities.mayfly) {
      player.abilities.mayfly = false
      player.abilities.flying = false
      player.displayClientMessage('Flying: ').append('disabled')), true)
    } else {
      player.abilities.mayfly = true
      player.displayClientMessage('Flying: ').append('enabled')), true)
    return 1

#Custom Command Event

The custom command event is fired when /kubejs custom_command is ran. It's cancellable.
The event can act as an easier way to create a custom command.
Here's an example of giving a player diamonds when they run /kubejs custom_command diamonds
ServerEvents.customCommand('diamonds', event => {
  event.player.give(Item.of('minecraft:diamond', 64))