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Worker

Worker 类代表 WebWorkerworker 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.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());

方法

Methods

evaluate

Added in: v1.8 worker.evaluate

返回 pageFunction 的返回值。

Returns the return value of pageFunction.

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:-0NaNInfinity-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

await worker.evaluate(pageFunction);
await worker.evaluate(pageFunction, arg);

参数

Arguments

在工作环境中评估的功能。

Function to be evaluated in the worker context.

传递给 pageFunction 的可选参数。

Optional argument to pass to pageFunction.

返回

Returns


evaluateHandle

Added in: v1.8 worker.evaluateHandle

pageFunction 的返回值作为 JSHandle 返回。

Returns the return value of pageFunction as a JSHandle.

worker.evaluate()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

await worker.evaluateHandle(pageFunction);
await worker.evaluateHandle(pageFunction, arg);

参数

Arguments

在工作环境中评估的功能。

Function to be evaluated in the worker context.

传递给 pageFunction 的可选参数。

Optional argument to pass to pageFunction.

返回

Returns


url

Added in: v1.8 worker.url

用法

Usage

worker.url();

返回

Returns


事件

Events

on('close')

Added in: v1.8 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', data => {});

事件数据

Event data