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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.

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());

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, arg);

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

evaluateHandle​

Added before v1.9 worker.evaluateHandle

将 expression 的返回值作为 JSHandle 返回。

¥Returns the return value of expression as a JSHandle.

Worker.evaluate() 和 Worker.evaluateHandle() 之间的唯一区别是 Worker.evaluateHandle() 返回 JSHandle。

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

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

¥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.

用法

¥Usage

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

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

url​

Added before v1.9 worker.url

用法

¥Usage

Worker.url();

返回

¥Returns

waitForClose​

Added in: v1.10 worker.waitForClose

执行操作并等待 Worker 关闭。

¥Performs action and waits for the Worker to close.

用法

¥Usage

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

参数

¥Arguments

  • options Worker.WaitForCloseOptions（可选）

    ¥options Worker.WaitForCloseOptions (optional)

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

等待的最长时间（以毫秒为单位）。默认为 30000（30 秒）。通过 0 禁用超时。可以使用 BrowserContext.setDefaultTimeout() 更改默认值。

¥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().

执行触发事件的操作的回调。

¥Callback that performs the action triggering the event.

返回

¥Returns

事件​

¥Events

onClose(handler)​

Added before v1.9 worker.onClose(handler)

当该专用 WebWorker 终止时触发。

¥Emitted when this dedicated WebWorker is terminated.

用法

¥Usage

Worker.onClose(handler)

事件数据

¥Event data