2.5 KiB
class: 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());
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)
event: Worker.close
- type: <[Worker]>
Emitted when this dedicated WebWorker is terminated.
async method: Worker.evaluate
- returns: <[Serializable]>
Returns the return value of [param: 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.
param: Worker.evaluate.pageFunction
- langs: js
pageFunction
<[function]|[string]>
Function to be evaluated in the worker context
param: Worker.evaluate.arg
arg
<[EvaluationArgument]>
Optional argument to pass to [param: pageFunction
]
async method: Worker.evaluateHandle
- returns: <[JSHandle]>
Returns the return value of [param: 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.
param: Worker.evaluateHandle.pageFunction
- langs: js
pageFunction
<[function]|[string]>
Function to be evaluated in the page context
param: Worker.evaluateHandle.arg
arg
<[EvaluationArgument]>
Optional argument to pass to [param: pageFunction
]
method: Worker.url
- returns: <[string]>