# class:worker ### class: Worker v0.9.0 Worker 类表示一个 [WebWorker](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API)。在页面对象上 `workercreated` 和 `workerdestroyed` 事件被触发，以标识 worker 的生命周期。 ``` 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()); ``` #### Methods - [worker.evaluate(pageFunction, ...args)](#?product=Puppeteer&version=v1.11.0&show=api-workerevaluatepagefunction-args)v0.9.0 - [worker.evaluateHandle(pageFunction, ...args)](#?product=Puppeteer&version=v1.11.0&show=api-workerevaluatehandlepagefunction-args)v0.9.0 - [worker.executionContext()](#?product=Puppeteer&version=v1.11.0&show=api-workerexecutioncontext)v0.9.0 - [worker.url()](#?product=Puppeteer&version=v1.11.0&show=api-workerurl)v0.9.0 ### Methods #### worker.evaluate(pageFunction, ...args)v0.9.0 - `pageFunction` <[function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function "Function")|[string](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type "String")> Function to be evaluated in the worker context - `...args` <...[Serializable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Description "Serializable")|[JSHandle](#?product=Puppeteer&version=v1.11.0&show=api-class-jshandle "JSHandle")> Arguments to pass to `pageFunction` - returns: <[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise")<[Serializable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Description "Serializable")>> Promise which resolves to the return value of `pageFunction` 如果传递给 `worker.evaluate` 的函数返回一个 [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise")，那么 `worker.evaluate` 将等待解析并返回它的值。 如果传递给 `worker.evaluate` 的函数返回一个 非\[序列化\]的值，那么 `worker.evaluate` 解析为 `undefined`。 [(await worker.executionContext()).evaluate(pageFunction, ...args)](#?product=Puppeteer&version=v1.11.0&show=api-executioncontextevaluatepagefunction-args) 的快捷链接。 #### worker.evaluateHandle(pageFunction, ...args)v0.9.0 - `pageFunction` <[function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function "Function")|[string](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type "String")> Function to be evaluated in the page context - `...args` <...[Serializable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Description "Serializable")|[JSHandle](#?product=Puppeteer&version=v1.11.0&show=api-class-jshandle "JSHandle")> Arguments to pass to `pageFunction` - returns: <[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise")<[JSHandle](#?product=Puppeteer&version=v1.11.0&show=api-class-jshandle "JSHandle")>> Promise which resolves to the return value of `pageFunction` as in-page object (JSHandle) `worker.evaluate` 和 `worker.evaluateHandle` 之间的唯一区别是 `worker.evaluateHandle` 返回页内对象（JSHandle）。 如果传递给 `worker.evaluateHandle` 的函数返回一个 [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise")，那么 `worker.evaluateHandle` 将等待解析并返回它的值。 [(await worker.executionContext()).evaluateHandle(pageFunction, ...args)](#?product=Puppeteer&version=v1.11.0&show=api-executioncontextevaluatehandlepagefunction-args) 的快捷链接。 #### worker.executionContext()v0.9.0 - returns: <[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise "Promise")<[ExecutionContext](#?product=Puppeteer&version=v1.11.0&show=api-class-executioncontext "ExecutionContext")>> #### worker.url()v0.9.0 - returns: <[string](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type "String")>  puppeteer.js中文网|class:worker puppeteer.js中文文档, puppeteer chrome, puppeteer firefox, puppeteer api 中文文档 puppeteer.js中文网包含了Puppeteer中文文档，最新资讯，应用案例等。Puppeteer 是一个 Node 库，它提供了一个高级 API 来通过 DevTools 协议控制 Chromium 或 Chrome。