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Worker

Worker 类表示一个 WebWorker。当创建工作进程时，会在页面对象上触发 worker 事件。当工作进程结束时，会在工作进程对象上触发 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.Worker += (_, worker) =>
{
    Console.WriteLine($"Worker created: {worker.Url}");
    worker.Close += (_, _) => Console.WriteLine($"Worker closed {worker.Url}");
};

Console.WriteLine("Current Workers:");
foreach(var pageWorker in page.Workers)
{
    Console.WriteLine($"\tWorker: {pageWorker.Url}");
}

方法​

🌐 Methods

EvaluateAsync​

Added before v1.9 worker.EvaluateAsync

返回 expression 的返回值。

🌐 Returns the return value of expression.

如果传递给 Worker.EvaluateAsync() 的函数返回一个 Promise，那么 Worker.EvaluateAsync() 会等待该 promise 解析完成并返回其值。

🌐 If the function passed to the Worker.EvaluateAsync() returns a Promise, then Worker.EvaluateAsync() would wait for the promise to resolve and return its value.

如果传递给 Worker.EvaluateAsync() 的函数返回一个非 Serializable 值，那么 Worker.EvaluateAsync() 将返回 undefined。Playwright 还支持传递一些不能被 JSON 序列化的额外值：-0、NaN、Infinity、-Infinity。

🌐 If the function passed to the Worker.EvaluateAsync() returns a non-Serializable value, then Worker.EvaluateAsync() returns undefined. Playwright also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity.

用法

await Worker.EvaluateAsync(expression, arg);

参数

  • expression string#

    将在浏览器上下文中求值的 JavaScript 表达式。如果表达式求值为一个函数，该函数将被自动调用。

  • arg EvaluationArgument? (optional)#

    可选参数，传递给 expression。

返回

  • [object]#

EvaluateHandleAsync​

Added before v1.9 worker.EvaluateHandleAsync

将 expression 的返回值作为 JSHandle 返回。

🌐 Returns the return value of expression as a JSHandle.

Worker.EvaluateAsync() 和 Worker.EvaluateHandleAsync() 之间的唯一区别是 Worker.EvaluateHandleAsync() 返回 JSHandle。

🌐 The only difference between Worker.EvaluateAsync() and Worker.EvaluateHandleAsync() is that Worker.EvaluateHandleAsync() returns JSHandle.

如果传递给 Worker.EvaluateHandleAsync() 的函数返回一个 Promise，那么 Worker.EvaluateHandleAsync() 将会等待该 promise 解决并返回其值。

🌐 If the function passed to the Worker.EvaluateHandleAsync() returns a Promise, then Worker.EvaluateHandleAsync() would wait for the promise to resolve and return its value.

用法

await Worker.EvaluateHandleAsync(expression, arg);

参数

  • expression string#

    将在浏览器上下文中求值的 JavaScript 表达式。如果表达式求值为一个函数，该函数将被自动调用。

  • arg EvaluationArgument? (optional)#

    可选参数，传递给 expression。

返回

Url​

Added before v1.9 worker.Url

用法

Worker.Url

返回

事件​

🌐 Events

event Close​

Added before v1.9 worker.event Close

当这个专用的 WebWorker 被终止时触发。

🌐 Emitted when this dedicated WebWorker is terminated.

用法

Worker.Close += async (_, worker) => {};

事件数据

event Console​

Added in: v1.57 worker.event Console

当 worker 中的 JavaScript 调用某个 console API 方法时触发，例如 console.log 或 console.dir。

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

用法

Worker.Console += async (_, consoleMessage) => {};

事件数据