HttpCrawler <Context>
Hierarchy
- BasicCrawler<Context>
- HttpCrawler
- CheerioCrawler
- JSDOMCrawler
- HttpCrawler
Index
Constructors
constructor
All
HttpCrawlerOptions
parameters are passed via an options object.Type parameters
- Context: InternalHttpCrawlingContext<any, any, HttpCrawler<Context>>
Parameters
options: HttpCrawlerOptions<Context> = {}
config: Configuration = ...
Returns HttpCrawler<Context>
Properties
optionalautoscaledPool
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 callingautoscaledPool.pause()
or to abort it by callingautoscaledPool.abort()
.
readonlyconfig
optionalproxyConfiguration
A reference to the underlying ProxyConfiguration class that manages the crawler's proxies. Only available if used by the crawler.
optionalrequestList
A reference to the underlying RequestList class that manages the crawler's requests. Only available if used by the crawler.
optionalrequestQueue
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
Default Router instance that will be used if we don't specify any requestHandler
.
See router.addHandler()
and router.addDefaultHandler()
.
optionalrunning
optionalsessionPool
A reference to the underlying SessionPool class that manages the crawler's sessions. Only available if used by the crawler.
readonlystats
A reference to the underlying Statistics class that collects and logs run statistics for requests.
Methods
addRequests
Adds requests to the queue in batches. By default, it will resolve after the initial batch is added, and continue adding the rest in background. You can configure the batch size via
batchSize
option and the sleep time in between the batches viawaitBetweenBatchesMillis
. If you want to wait for all batches to be added to the queue, you can use thewaitForAllRequestsToBeAdded
promise you get in the response object.Parameters
requests: (string | Source)[]
The requests to add
options: CrawlerAddRequestsOptions = {}
Options for the request queue
Returns Promise<CrawlerAddRequestsResult>
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 runningcrawler.addRequests()
before thecrawler.run()
.Parameters
optionalrequests: (string | RequestOptions<Dictionary> | Request<Dictionary>)[]
The requests to add
optionaloptions: CrawlerRunOptions
Options for the request queue
Returns Promise<FinalStatistics>
setStatusMessage
This method is periodically called by the crawler, every
statusMessageLoggingInterval
seconds.Parameters
message: string
options: SetStatusMessageOptions = {}
Returns undefined | Promise<void>
use
EXPERIMENTAL Function for attaching CrawlerExtensions such as the Unblockers.
Parameters
extension: CrawlerExtension
Crawler extension that overrides the crawler configuration.
Returns void
useState
Type parameters
- State: Dictionary = Dictionary
Parameters
defaultValue: State = ...
Returns Promise<State>
Provides a framework for the parallel crawling of web pages using plain HTTP requests. 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.
It is very fast and efficient on data bandwidth. However, if the target website requires JavaScript to display the content, you might need to use PuppeteerCrawler or PlaywrightCrawler instead, because it loads the pages using full-featured headless Chrome browser.
This crawler downloads each URL using a plain HTTP request and doesn't do any HTML parsing.
The source URLs are represented using Request objects that are fed from RequestList or RequestQueue instances provided by the HttpCrawlerOptions.requestList or HttpCrawlerOptions.requestQueue constructor options, respectively.
If both HttpCrawlerOptions.requestList and HttpCrawlerOptions.requestQueue are used, the instance first processes URLs from the RequestList and automatically enqueues all of them to 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.
We can use the
preNavigationHooks
to adjustgotOptions
:By default, this crawler only processes web pages with the
text/html
andapplication/xhtml+xml
MIME content types (as reported by theContent-Type
HTTP header), and skips pages with other content types. If you want the crawler to process other content types, use the HttpCrawlerOptions.additionalMimeTypes constructor option. Beware that the parsing behavior differs for HTML, XML, JSON and other types of content. For details, see HttpCrawlerOptions.requestHandler.New requests are only dispatched 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 constructor. For user convenience, theminConcurrency
andmaxConcurrency
AutoscaledPool options are available directly in the constructor.Example usage: