WebWorker class

This class represents a WebWorker.

Signature

export declare abstract class WebWorker extends EventEmitter<Record<EventType, unknown>>

Extends: EventEmitter<Record<EventType, unknown>>

Remarks

The events workercreated and workerdestroyed are emitted on the page object to signal the worker lifecycle.

The constructor for this class is marked as internal. Third-party code should not call the constructor directly or create subclasses that extend the WebWorker class.

Example

page.on('workercreated', worker =>
  console.log('Worker created: ' + worker.url()),
);
page.on('workerdestroyed', worker =>
  console.log('Worker destroyed: ' + worker.url()),
);

console.log('Current workers:');
for (const worker of page.workers()) {
  console.log('  ' + worker.url());
}

Properties

Property Modifiers Type Description
client `readonly` [CDPSession](./puppeteer.cdpsession.md) The CDP session client the WebWorker belongs to.

Methods

Method Modifiers Description
[close()](./puppeteer.webworker.close.md)
[evaluate(func, args)](./puppeteer.webworker.evaluate.md) Evaluates a given function in the [worker](./puppeteer.webworker.md). **Remarks:** If the given function returns a promise, [evaluate](./puppeteer.webworker.evaluate.md) will wait for the promise to resolve. As a rule of thumb, if the return value of the given function is more complicated than a JSON object (e.g. most classes), then [evaluate](./puppeteer.webworker.evaluate.md) will \_likely\_ return some truncated value (or `{}`). This is because we are not returning the actual return value, but a deserialized version as a result of transferring the return value through a protocol to Puppeteer. In general, you should use [evaluateHandle](./puppeteer.webworker.evaluatehandle.md) if [evaluate](./puppeteer.webworker.evaluate.md) cannot serialize the return value properly or you need a mutable [handle](./puppeteer.jshandle.md) to the return object.
[evaluateHandle(func, args)](./puppeteer.webworker.evaluatehandle.md) Evaluates a given function in the [worker](./puppeteer.webworker.md). **Remarks:** If the given function returns a promise, [evaluate](./puppeteer.webworker.evaluate.md) will wait for the promise to resolve. In general, you should use [evaluateHandle](./puppeteer.webworker.evaluatehandle.md) if [evaluate](./puppeteer.webworker.evaluate.md) cannot serialize the return value properly or you need a mutable [handle](./puppeteer.jshandle.md) to the return object.
[url()](./puppeteer.webworker.url.md) The URL of this web worker.