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abstractBrowserCrawler <InternalBrowserPoolOptions, LaunchOptions, Context, GoToOptions>

Provides a simple framework for parallel crawling of web pages using headless browsers with Puppeteer and Playwright. The URLs to crawl are fed either from a static list of URLs or from a dynamic queue of URLs enabling recursive crawling of websites.

Since BrowserCrawler uses headless (or even headful) browsers to download web pages and extract data, it is useful for crawling of websites that require to execute JavaScript. If the target website doesn’t need JavaScript, we should consider using the CheerioCrawler, which downloads the pages using raw HTTP requests and is about 10x faster.

The source URLs are represented by the Request objects that are fed from the RequestList or RequestQueue instances provided by the requestList or requestQueue constructor options, respectively. If neither requestList nor requestQueue options are provided, the crawler will open the default request queue either when the crawler.addRequests() function is called, or if requests parameter (representing the initial requests) of the crawler.run() function is provided.

If both requestList and requestQueue options are used, the instance first processes URLs from the RequestList and automatically enqueues all of them to the RequestQueue before it starts their processing. This ensures that a single URL is not crawled multiple times.

The crawler finishes when there are no more Request objects to crawl.

BrowserCrawler opens a new browser page (i.e. tab or window) for each Request object to crawl and then calls the function provided by user as the requestHandler option.

New pages are only opened when there is enough free CPU and memory available, using the functionality provided by the AutoscaledPool class. All AutoscaledPool configuration options can be passed to the autoscaledPoolOptions parameter of the BrowserCrawler constructor. For user convenience, the minConcurrency and maxConcurrency options of the underlying AutoscaledPool constructor are available directly in the BrowserCrawler constructor.

NOTE: the pool of browser instances is internally managed by the BrowserPool class.

Hierarchy

Index

Properties

optionalautoscaledPool

autoscaledPool?: AutoscaledPool

A reference to the underlying AutoscaledPool class that manages the concurrency of the crawler.

NOTE: This property is only initialized after calling the crawler.run() function. We can use it to change the concurrency settings on the fly, to pause the crawler by calling autoscaledPool.pause() or to abort it by calling autoscaledPool.abort().

browserPool

browserPool: BrowserPool<InternalBrowserPoolOptions, InferBrowserPluginArray<InternalBrowserPoolOptions[browserPlugins], []>, ReturnType<InferBrowserPluginArray<InternalBrowserPoolOptions[browserPlugins], []>[number][createController]>, ReturnType<InferBrowserPluginArray<InternalBrowserPoolOptions[browserPlugins], []>[number][createLaunchContext]>, Parameters<ReturnType<InferBrowserPluginArray<InternalBrowserPoolOptions[browserPlugins], []>[number][createController]>[newPage]>[0], UnwrapPromise<ReturnType<ReturnType<InferBrowserPluginArray<InternalBrowserPoolOptions[browserPlugins], []>[number][createController]>[newPage]>>>

A reference to the underlying BrowserPool class that manages the crawler’s browsers.

readonlyconfig

config: Configuration = ...

launchContext

launchContext: BrowserLaunchContext<LaunchOptions, unknown>

optionalproxyConfiguration

proxyConfiguration?: ProxyConfiguration

A reference to the underlying ProxyConfiguration class that manages the crawler’s proxies. Only available if used by the crawler.

optionalrequestList

requestList?: RequestList

A reference to the underlying RequestList class that manages the crawler’s requests. Only available if used by the crawler.

optionalrequestQueue

requestQueue?: RequestQueue

Dynamic queue of URLs to be processed. This is useful for recursive crawling of websites. A reference to the underlying RequestQueue class that manages the crawler’s requests. Only available if used by the crawler.

readonlyrouter

router: RouterHandler<Context> = ...

Default Router instance that will be used if we don’t specify any requestHandler. See router.addHandler() and router.addDefaultHandler().

optionalsessionPool

sessionPool?: SessionPool

A reference to the underlying SessionPool class that manages the crawler’s sessions. Only available if used by the crawler.

readonlystats

stats: Statistics

A reference to the underlying Statistics class that collects and logs run statistics for requests.

Methods

addRequests

getRequestQueue

  • Returns Promise<RequestQueue>

run

  • Runs the crawler. Returns a promise that gets resolved once all the requests are processed. We can use the requests parameter to enqueue the initial requests - it is a shortcut for running crawler.addRequests() before the crawler.run().


    Parameters

    Returns Promise<FinalStatistics>

useState

  • useState<State>(defaultValue?: State): Promise<State>
  • Type parameters

    • State: Dictionary<any> = Dictionary<any>

    Parameters

    • defaultValue: State = ...

    Returns Promise<State>