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.
- worker.on("close")
- worker.evaluate(expression, **kwargs)
- worker.evaluate_handle(expression, **kwargs)
- worker.url
#
worker.on("close")- type: <Worker>
Emitted when this dedicated WebWorker is terminated.
#
worker.evaluate(expression, **kwargs)expression
<str> JavaScript expression to be evaluated in the browser context. If it looks like a function declaration, it is interpreted as a function. Otherwise, evaluated as an expression.arg
<[EvaluationArgument]> Optional argument to pass toexpression
.- returns: <Serializable>
Returns the return value of expression
.
If the function passed to the worker.evaluate(expression, **kwargs) returns a Promise, then worker.evaluate(expression, **kwargs) would wait for the promise to resolve and return its value.
If the function passed to the worker.evaluate(expression, **kwargs) returns a non-Serializable value, then worker.evaluate(expression, **kwargs) returns undefined
. Playwright also supports transferring some additional values that are not serializable by JSON
: -0
, NaN
, Infinity
, -Infinity
.
#
worker.evaluate_handle(expression, **kwargs)expression
<str> JavaScript expression to be evaluated in the browser context. If it looks like a function declaration, it is interpreted as a function. Otherwise, evaluated as an expression.arg
<[EvaluationArgument]> Optional argument to pass toexpression
.- returns: <JSHandle>
Returns the return value of expression
as a JSHandle.
The only difference between worker.evaluate(expression, **kwargs) and worker.evaluate_handle(expression, **kwargs) is that worker.evaluate_handle(expression, **kwargs) returns JSHandle.
If the function passed to the worker.evaluate_handle(expression, **kwargs) returns a Promise, then worker.evaluate_handle(expression, **kwargs) would wait for the promise to resolve and return its value.
#
worker.url- returns: <str>