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Worker

Worker 类代表 WebWorker。worker 事件在页面对象上触发，以指示工作线程创建。当工作线程消失时，工作线程对象上会触发 close 事件。

¥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.

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)

方法​

¥Methods

evaluate​

Added before v1.9 worker.evaluate

返回 expression 的返回值。

¥Returns the return value of expression.

如果传递给 worker.evaluate() 的函数返回 Promise，那么 worker.evaluate() 将等待 Promise 解析并返回其值。

¥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.

如果传递给 worker.evaluate() 的函数返回非 可串行化 值，则 worker.evaluate() 返回 undefined。Playwright 还支持传输一些 JSON 无法序列化的附加值：-0、NaN、Infinity、-Infinity。

¥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.

用法

¥Usage

worker.evaluate(expression)
worker.evaluate(expression, **kwargs)

参数

¥Arguments

要在浏览器上下文中执行的 JavaScript 表达式。如果表达式的计算结果为函数，则会自动调用该函数。

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

传递给 expression 的可选参数。

¥Optional argument to pass to expression.

返回

¥Returns

evaluate_handle​

Added before v1.9 worker.evaluate_handle

将 expression 的返回值作为 JSHandle 返回。

¥Returns the return value of expression as a JSHandle.

worker.evaluate() 和 worker.evaluate_handle() 之间的唯一区别是 worker.evaluate_handle() 返回 JSHandle。

¥The only difference between worker.evaluate() and worker.evaluate_handle() is that worker.evaluate_handle() returns JSHandle.

如果传递给 worker.evaluate_handle() 的函数返回 Promise，那么 worker.evaluate_handle() 将等待 Promise 解析并返回其值。

¥If the function passed to the worker.evaluate_handle() returns a Promise, then worker.evaluate_handle() would wait for the promise to resolve and return its value.

用法

¥Usage

worker.evaluate_handle(expression)
worker.evaluate_handle(expression, **kwargs)

参数

¥Arguments

要在浏览器上下文中执行的 JavaScript 表达式。如果表达式的计算结果为函数，则会自动调用该函数。

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

传递给 expression 的可选参数。

¥Optional argument to pass to expression.

返回

¥Returns

属性​

¥Properties

url​

Added before v1.9 worker.url

用法

¥Usage

worker.url

返回

¥Returns

事件​

¥Events

on("close")​

Added before v1.9 worker.on("close")

当该专用 WebWorker 终止时触发。

¥Emitted when this dedicated WebWorker is terminated.

用法

¥Usage

worker.on("close", handler)

事件数据

¥Event data