wails/website/versioned_docs/version-v2.7.0/reference/runtime/events.mdx

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# Events

The Wails runtime provides a unified events system, where events can be emitted or received by either Go or JavaScript.
Optionally, data may be passed with the events. Listeners will receive the data in the local data types.

### EventsOn

This method sets up a listener for the given event name. When an event of type `eventName` is [emitted](#EventsEmit),
the callback is triggered. Any additional data sent with the emitted event will be passed to the callback. It returns
a function to cancel the listener.

Go: `EventsOn(ctx context.Context, eventName string, callback func(optionalData ...interface{})) func()`<br/>
JS: `EventsOn(eventName string, callback function(optionalData?: any)): () => void`

### EventsOff

This method unregisters the listener for the given event name, optionally multiple listeneres can be unregistered via `additionalEventNames`.

Go: `EventsOff(ctx context.Context, eventName string, additionalEventNames ...string)`<br/>
JS: `EventsOff(eventName string, ...additionalEventNames)`

### EventsOnce

This method sets up a listener for the given event name, but will only trigger once. It returns a function to cancel
the listener.

Go: `EventsOnce(ctx context.Context, eventName string, callback func(optionalData ...interface{})) func()`<br/>
JS: `EventsOnce(eventName string, callback function(optionalData?: any)): () => void`

### EventsOnMultiple

This method sets up a listener for the given event name, but will only trigger a maximum of `counter` times. It returns
a function to cancel the listener.

Go: `EventsOnMultiple(ctx context.Context, eventName string, callback func(optionalData ...interface{}), counter int) func()`<br/>
JS: `EventsOnMultiple(eventName string, callback function(optionalData?: any), counter int): () => void`

### EventsEmit

This method emits the given event. Optional data may be passed with the event. This will trigger any event listeners.

Go: `EventsEmit(ctx context.Context, eventName string, optionalData ...interface{})`<br/>
JS: `EventsEmit(eventName: string, ...optionalData: any)`