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')
- worker.evaluate(pageFunction[, arg])
- worker.evaluateHandle(pageFunction[, arg])
- worker.url()
worker.on('close')#
- type: <Worker>
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 topageFunction.#- returns: <Promise<Serializable>>#
Returns the return value of pageFunction.
If the function passed to the worker.evaluate(pageFunction[, arg]) returns a Promise, then worker.evaluate(pageFunction[, arg]) would wait for the promise to resolve and return its value.
If the function passed to the worker.evaluate(pageFunction[, arg]) returns a non-Serializable value, then worker.evaluate(pageFunction[, arg]) returns undefined. Playwright also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity.
worker.evaluateHandle(pageFunction[, arg])#
pageFunction<function|string> Function to be evaluated in the worker context.#arg<EvaluationArgument> Optional argument to pass topageFunction.#- returns: <Promise<JSHandle>>#
Returns the return value of pageFunction as a JSHandle.
The only difference between worker.evaluate(pageFunction[, arg]) and worker.evaluateHandle(pageFunction[, arg]) is that worker.evaluateHandle(pageFunction[, arg]) returns JSHandle.
If the function passed to the worker.evaluateHandle(pageFunction[, arg]) returns a Promise, then worker.evaluateHandle(pageFunction[, arg]) would wait for the promise to resolve and return its value.