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class: Worker

Added in: v1.8

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());
page.onWorker(worker -> {
  System.out.println("Worker created: " + worker.url());
  worker.onClose(worker1 -> System.out.println("Worker destroyed: " + worker1.url()));
});
System.out.println("Current workers:");
for (Worker worker : page.workers())
  System.out.println("  " + worker.url());
def handle_worker(worker):
    print("worker created: " + worker.url)
    worker.on("close", lambda: print("worker destroyed: " + worker.url))

page.on('worker', handle_worker)

print("current workers:")
for worker in page.workers:
    print("    " + worker.url)
page.Worker += (_, worker) =>
{
    Console.WriteLine($"Worker created: {worker.Url}");
    worker.Close += (_, _) => Console.WriteLine($"Worker closed {worker.Url}");
};

Console.WriteLine("Current Workers:");
foreach(var pageWorker in page.Workers)
{
    Console.WriteLine($"\tWorker: {pageWorker.Url}");
}

event: Worker.close​

Added in: v1.8

  • argument: <Worker>

Emitted when this dedicated WebWorker is terminated.

event: Worker.console​

Added in: v1.57

  • argument: <ConsoleMessage>

Emitted when JavaScript within the worker calls one of console API methods, e.g. console.log or console.dir.

async method: Worker.evaluate​

Added in: v1.8 Returns: Serializable

Returns the return value of expression.

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. copilotbrowser also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity.

param: Worker.evaluate.expression = %%-evaluate-expression-%%​

Added in: v1.8

param: Worker.evaluate.expression = %%-js-worker-evaluate-workerfunction-%%​

Added in: v1.8

param: Worker.evaluate.arg​

Added in: v1.8

  • arg ?<EvaluationArgument>

Optional argument to pass to expression.

async method: Worker.evaluateHandle​

Added in: v1.8 Returns: JSHandle

Returns the return value of expression as a JSHandle.

The only difference between Worker.evaluate() and Worker.evaluateHandle() is that Worker.evaluateHandle() returns 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.

param: Worker.evaluateHandle.expression = %%-evaluate-expression-%%​

Added in: v1.8

param: Worker.evaluateHandle.expression = %%-js-worker-evaluate-workerfunction-%%​

Added in: v1.8

param: Worker.evaluateHandle.arg​

Added in: v1.8

  • arg ?<EvaluationArgument>

Optional argument to pass to expression.

method: Worker.url​

Added in: v1.8 Returns: string

async method: Worker.waitForClose​

Added in: v1.10

Languages: Java Returns: Worker

Performs action and waits for the Worker to close.

option: Worker.waitForClose.timeout = %%-wait-for-event-timeout-%%​

Added in: v1.9

param: Worker.waitForClose.callback = %%-java-wait-for-event-callback-%%​

Added in: v1.9

async method: Worker.waitForConsoleMessage​

Added in: v1.57

Languages: Java Returns: ConsoleMessage

Performs action and waits for a console message.

option: Worker.waitForConsoleMessage.predicate​

Added in: v1.57

  • predicate <function(ConsoleMessage):boolean>

Receives the ConsoleMessage object and resolves to true when the waiting should resolve.

option: Worker.waitForConsoleMessage.timeout = %%-wait-for-event-timeout-%%​

Added in: v1.57

param: Worker.waitForConsoleMessage.callback = %%-java-wait-for-event-callback-%%​

Added in: v1.57

async method: Worker.waitForEvent​

Added in: v1.57

Languages: JavaScript, Python Returns: any

Waits for event to fire and passes its value into the predicate function. Returns when the predicate returns truthy value. Will throw an error if the page is closed before the event is fired. Returns the event data value.

Usage

// Start waiting for download before clicking. Note no await.
const consolePromise = worker.waitForEvent('console');
await worker.evaluate('console.log(42)');
const consoleMessage = await consolePromise;
async with worker.expect_event("console") as event_info:
    await worker.evaluate("console.log(42)")
message = await event_info.value
with worker.expect_event("console") as event_info:
    worker.evaluate("console.log(42)")
message = event_info.value

async method: Worker.waitForEvent​

Added in: v1.57

Languages: Python Returns: EventContextManager

param: Worker.waitForEvent.event = %%-wait-for-event-event-%%​

Added in: v1.57

param: Worker.waitForEvent.optionsOrPredicate​

Added in: v1.57

Languages: JavaScript

  • optionsOrPredicate ?<function|Object>
    • predicate <function> Receives the event data and resolves to truthy value when the waiting should resolve.
    • timeout ?<float> Maximum time to wait for in milliseconds. Defaults to 0 - no timeout. The default value can be changed via actionTimeout option in the config, or by using the BrowserContext.setDefaultTimeout() or Page.setDefaultTimeout() methods.

Either a predicate that receives an event or an options object. Optional.

option: Worker.waitForEvent.predicate = %%-wait-for-event-predicate-%%​

Added in: v1.57

option: Worker.waitForEvent.timeout = %%-wait-for-event-timeout-%%​

Added in: v1.57