puppeteer/website/versioned_docs/version-9.1.1/puppeteer.eventemitter.once.md

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[Home](./index.md) &gt; [puppeteer](./puppeteer.md) &gt; [EventEmitter](./puppeteer.eventemitter.md) &gt; [once](./puppeteer.eventemitter.once.md)
## EventEmitter.once() method
Like `on` but the listener will only be fired once and then it will be removed.
<b>Signature:</b>
```typescript
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 |
<b>Returns:</b>
[EventEmitter](./puppeteer.eventemitter.md)
`this` to enable you to chain method calls.