Events

The Events system is the primary communication mechanism in HELIX. It enables structured data transfer between the client and server using global registration and triggering functions. Events support strings, numbers, booleans, nil, vectors, and tables as arguments.

tip

The triggering controller is passed automatically as the first parameter when a client triggers a server event -- similar to how source is passed in FiveM.

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Core Functions

Function	Parameters	Authority	Description
RegisterClientEvent	name: string, callback: function	Client	Registers a client-side event handler. Called when the server triggers an event targeted at this client.
RegisterServerEvent	name: string, callback: function	Server	Registers a server-side event handler. The triggering player controller is automatically passed as the first argument.
TriggerClientEvent	controller: PlayerController, name: string, ...args: any	Server	Sends an event from the server to a specific client. All extra arguments are serialized and passed to the client handler.
TriggerLocalClientEvent	name: string, ...args: any	Client	Sends an event from a client script to another client-side Lua package on the same client.
TriggerServerEvent	name: string, ...args: any	Client	Sends an event from the client to the server. The triggering controller is passed automatically as the first argument to the server handler.
TriggerLocalServerEvent	name: string, ...args: any	Server	Sends an event from a server script to another server-side Lua package, enabling cross-package communication without client involvement.
BroadcastEvent	name: string, ...args: any	Server	Sends an event from the server to all connected clients.

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Examples

Registering and Triggering Events

Blueprint

Blueprint— Register and Trigger Client EventScroll to zoom · Drag to pan · Drag nodes to move

Lua

-- CLIENT SCRIPT: Register a client event
RegisterClientEvent('TestClient', function(str, num, bool, nil_val, vec, tbl)
    print('CLIENT TestClient EVENT')
    print('  String:', str, 'Type:', type(str))
    print('  Number:', num, 'Type:', type(num))
    print('  Boolean:', bool, 'Type:', type(bool))
    print('  Vector:', vec, 'Type:', type(vec))
    print('  Table:', tbl, 'Type:', type(tbl))
end)

-- CLIENT SCRIPT: Trigger a server event from the client
TriggerServerEvent('TestServer', 'Hello from Client', 100, true, nil, Vector(100, 100, 100), { key = 'value' })

JavaScript

// Client-side event registration and triggering follows
// the same pattern in JavaScript.
// Refer to the Lua examples for the function signatures.

Server-Side Event Handling

Blueprint

Blueprint— Server Event Handler with ResponseScroll to zoom · Drag to pan · Drag nodes to move

Lua

-- SERVER SCRIPT: Register a server event
RegisterServerEvent('TestServer', function(controller, str, num, bool, nil_val, vec, tbl)
    print('SERVER TestServer EVENT from', controller)
    print('  String:', str)
    print('  Number:', num)

    -- Send a response back to the triggering client
    TriggerClientEvent(controller, 'TestClient', str, num, bool, nil_val, vec, tbl)
end)

-- SERVER SCRIPT: Broadcast to all clients
BroadcastEvent('myClientEvent', 100)

JavaScript

// Server-side event registration follows the same pattern.
// Refer to the Lua examples for function signatures.

Cross-Package Communication

Blueprint

Blueprint— Cross-Package Event CommunicationScroll to zoom · Drag to pan · Drag nodes to move

Lua

-- CLIENT: Trigger a local client event (client -> client, same machine)
TriggerLocalClientEvent('TestClient', "Hello", 100, true, nil, Vector(100, 100, 100), { value = 42 })

-- SERVER: Trigger a local server event (server -> server, cross-package)
TriggerLocalServerEvent('TestServer', 'Cross-package data', 100, true, nil, Vector(100, 100, 100), { key = 'value' })

JavaScript

// Local event triggering follows the same pattern.
// Refer to the Lua examples for function signatures.

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caution

Events send data over the network. Supported argument types include strings, numbers, booleans, nil, vectors, and tables. Function references and complex objects cannot be sent remotely.