--- sidebar_label: CommonEventEmitter.on --- # CommonEventEmitter.on() method **Signature:** ```typescript interface CommonEventEmitter { on(event: EventType, handler: Handler): CommonEventEmitter; } ``` ## Parameters | Parameter | Type | Description | | --------- | ------------------------------------- | ----------- | | event | [EventType](./puppeteer.eventtype.md) | | | handler | [Handler](./puppeteer.handler.md) | | **Returns:** [CommonEventEmitter](./puppeteer.commoneventemitter.md)