Version: 1.8.0

Worker

The Worker class represents a WebWorker. worker event is emitted on the page object to signal a worker creation. close event is emitted on the worker object when the worker is gone.

page.on('worker', worker => {
console.log('Worker created: ' + worker.url());
worker.on('close', worker => console.log('Worker destroyed: ' + worker.url()));
});
console.log('Current workers:');
for (const worker of page.workers())
console.log(' ' + worker.url());

worker.on('close')#

Emitted when this dedicated WebWorker is terminated.

worker.evaluate(pageFunction[, arg])#

  • pageFunction <function|string> Function to be evaluated in the worker context
  • arg <[EvaluationArgument]> Optional argument to pass to pageFunction
  • returns: <Promise<Serializable>>

Returns the return value of pageFunction

If the function passed to the worker.evaluate returns a Promise, then worker.evaluate would wait for the promise to resolve and return its value.

If the function passed to the worker.evaluate returns a non-Serializable value, then worker.evaluate returns undefined. DevTools Protocol also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity, and bigint literals.

worker.evaluateHandle(pageFunction[, arg])#

  • pageFunction <function|string> Function to be evaluated in the page context
  • arg <[EvaluationArgument]> Optional argument to pass to pageFunction
  • returns: <Promise<JSHandle>>

Returns the return value of pageFunction as in-page object (JSHandle).

The only difference between worker.evaluate and worker.evaluateHandle is that worker.evaluateHandle returns in-page object (JSHandle).

If the function passed to the worker.evaluateHandle returns a Promise, then worker.evaluateHandle would wait for the promise to resolve and return its value.

worker.url()#