class: Worker

3.1.0

3.1.0

The Worker class represents a WebWorker.

The events workercreated and workerdestroyed are emitted on the page object to signal the worker lifecycle.

page.on('workercreated', worker => console.log('Worker created: ' + worker.url()));
page.on('workerdestroyed', worker => console.log('Worker destroyed: ' + worker.url()));

console.log('Current workers:');
for (const worker of page.workers())
  console.log('  ' + worker.url());

worker.evaluate(pageFunction[, ...args])

• pageFunction <[function]|[string]> Function to be evaluated in the worker context
• ...args <...[Serializable]|[JSHandle]> Arguments to pass to pageFunction
• returns: <[Promise]<[Serializable]>> Promise which resolves to the return value of pageFunction

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.

If the function passed to the worker.evaluate returns a non-[Serializable] value, then worker.evaluate resolves to undefined. DevTools Protocol also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity, and bigint literals.

Shortcut for (await worker.executionContext()).evaluate(pageFunction, ...args).

worker.evaluateHandle(pageFunction[, ...args])

• pageFunction <[function]|[string]> Function to be evaluated in the page context
• ...args <...[Serializable]|[JSHandle]> Arguments to pass to pageFunction
• returns: <[Promise]<[JSHandle]>> Promise which resolves to the return value of pageFunction as in-page object (JSHandle)

The only difference between worker.evaluate and worker.evaluateHandle is that worker.evaluateHandle returns in-page object (JSHandle).

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.

Shortcut for (await worker.executionContext()).evaluateHandle(pageFunction, ...args).

worker.executionContext()

• returns: <[Promise]<[ExecutionContext]>>

worker.url()

• returns: <[string]>

The Worker class represents a WebWorker.
The events workercreated and workerdestroyed are emitted on the page object to signal the worker lifecycle.

page.on('workercreated', worker => console.log('Worker created: ' + worker.url()));
page.on('workerdestroyed', worker => console.log('Worker destroyed: ' + worker.url()));

console.log('Current workers:');
for (const worker of page.workers())
  console.log('  ' + worker.url());

worker.evaluate(pageFunction[, ...args])

• pageFunction <[function]|[string]> Function to be evaluated in the worker context
• ...args <...[Serializable]|[JSHandle]> Arguments to pass to pageFunction
• returns: <[Promise]<[Serializable]>> Promise which resolves to the return value of pageFunction

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.

If the function passed to the worker.evaluate returns a non-[Serializable] value, then worker.evaluate resolves to undefined. DevTools Protocol also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity, and bigint literals.

Shortcut for (await worker.executionContext()).evaluate(pageFunction, ...args).

worker.evaluateHandle(pageFunction[, ...args])

• pageFunction <[function]|[string]> Function to be evaluated in the page context
• ...args <...[Serializable]|[JSHandle]> Arguments to pass to pageFunction
• returns: <[Promise]<[JSHandle]>> Promise which resolves to the return value of pageFunction as in-page object (JSHandle)

The only difference between worker.evaluate and worker.evaluateHandle is that worker.evaluateHandle returns in-page object (JSHandle).

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.

Shortcut for (await worker.executionContext()).evaluateHandle(pageFunction, ...args).

worker.executionContext()

• returns: <[Promise]<[ExecutionContext]>>

worker.url()

• returns: <[string]>

The Worker class represents a WebWorker.
The events workercreated and workerdestroyed are emitted on the page object to signal the worker lifecycle.

page.on('workercreated', worker => console.log('Worker created: ' + worker.url()));
page.on('workerdestroyed', worker => console.log('Worker destroyed: ' + worker.url()));

console.log('Current workers:');
for (const worker of page.workers())
  console.log('  ' + worker.url());

worker.evaluate(pageFunction[, ...args])

• pageFunction <[function]|[string]> Function to be evaluated in the worker context
• ...args <...[Serializable]|[JSHandle]> Arguments to pass to pageFunction
• returns: <[Promise]<[Serializable]>> Promise which resolves to the return value of pageFunction

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.

If the function passed to the worker.evaluate returns a non-[Serializable] value, then worker.evaluate resolves to undefined. DevTools Protocol also supports transferring some additional values that are not serializable by JSON: -0, NaN, Infinity, -Infinity, and bigint literals.

Shortcut for (await worker.executionContext()).evaluate(pageFunction, ...args).

worker.evaluateHandle(pageFunction[, ...args])

• pageFunction <[function]|[string]> Function to be evaluated in the page context
• ...args <...[Serializable]|[JSHandle]> Arguments to pass to pageFunction
• returns: <[Promise]<[JSHandle]>> Promise which resolves to the return value of pageFunction as in-page object (JSHandle)

The only difference between worker.evaluate and worker.evaluateHandle is that worker.evaluateHandle returns in-page object (JSHandle).

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.

Shortcut for (await worker.executionContext()).evaluateHandle(pageFunction, ...args).

worker.executionContext()

• returns: <[Promise]<[ExecutionContext]>>

worker.url()

• returns: <[string]>

Worker 类代表 WebWorker。
在页面对象上发出事件workercreated和workerdestroyed，以指示工作程序生命周期。

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原文地址：https://learnku.com/docs/puppeteer/3.1.0...

译文地址：https://learnku.com/docs/puppeteer/3.1.0...