GeezerVison

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.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());

Methods​

evaluate​

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

Usage

Worker.evaluate(expression);
Worker.evaluate(expression, arg);

Arguments

• expression String#

  JavaScript expression to be evaluated in the browser context. If the expression evaluates to a function, the function is automatically invoked.

• arg EvaluationArgument (optional)#

  Optional argument to pass to expression.

Returns

• Object#

evaluateHandle​

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.

Usage

Worker.evaluateHandle(expression);
Worker.evaluateHandle(expression, arg);

Arguments

• expression String#

  JavaScript expression to be evaluated in the browser context. If the expression evaluates to a function, the function is automatically invoked.

• arg EvaluationArgument (optional)#

  Optional argument to pass to expression.

Returns

• JSHandle#

url​

Usage

Worker.url();

Returns

• String#

waitForClose​

Performs action and waits for the Worker to close.

Usage

Worker.waitForClose(callback);
Worker.waitForClose(callback, options);

Arguments

• options Worker.WaitForCloseOptions (optional)

  • setTimeout double (optional) Added in: v1.9#

    Maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout. The default value can be changed by using the BrowserContext.setDefaultTimeout().

• callback Runnable Added in: v1.9#

  Callback that performs the action triggering the event.

Returns

• Worker#

waitForConsoleMessage​

Performs action and waits for a console message.

Usage

Worker.waitForConsoleMessage(callback);
Worker.waitForConsoleMessage(callback, options);

Arguments

• options Worker.WaitForConsoleMessageOptions (optional)

  • setPredicate Predicate<ConsoleMessage> (optional)#

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

  • setTimeout double (optional)#

    Maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout. The default value can be changed by using the BrowserContext.setDefaultTimeout().

• callback Runnable#

  Callback that performs the action triggering the event.

Returns

• ConsoleMessage#

Events​

onClose(handler)​

Emitted when this dedicated WebWorker is terminated.

Usage

Worker.onClose(handler)

Event data

• Worker

onConsole(handler)​

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

Usage

Worker.onConsole(handler)

Event data

• ConsoleMessage