puppeteer/docs/api/puppeteer.eventemitter.once.md

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---
sidebar_label: EventEmitter.once
---
# EventEmitter.once() method
Like `on` but the listener will only be fired once and then it will be removed.
**Signature:**
```typescript
class EventEmitter {once(event: EventType, handler: Handler): EventEmitter;}
```
## Parameters
| Parameter | Type | Description |
| --- | --- | --- |
| event | [EventType](./puppeteer.eventtype.md) | the event you'd like to listen to |
| handler | [Handler](./puppeteer.handler.md) | the handler function to run when the event occurs |
**Returns:**
[EventEmitter](./puppeteer.eventemitter.md)
`this` to enable you to chain method calls.