@crawlee/linkedom

Provides a framework for the parallel crawling of web pages using plain HTTP requests and linkedom DOM implementation. 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 LinkeDOMCrawler uses raw HTTP requests to download web pages, 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.

LinkeDOMCrawler downloads each URL using a plain HTTP request, parses the HTML content using LinkeDOM and then invokes the user-provided LinkeDOMCrawlerOptions.requestHandler to extract page data using the window object.

The source URLs are represented using Request objects that are fed from RequestList or RequestQueue instances provided by the LinkeDOMCrawlerOptions.requestList or LinkeDOMCrawlerOptions.requestQueue constructor options, respectively.

If both LinkeDOMCrawlerOptions.requestList and LinkeDOMCrawlerOptions.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 adjust gotOptions:

preNavigationHooks: [
    (crawlingContext, gotOptions) => {
        // ...
    },
]

By default, LinkeDOMCrawler only processes web pages with the text/html and application/xhtml+xml MIME content types (as reported by the Content-Type HTTP header), and skips pages with other content types. If you want the crawler to process other content types, use the LinkeDOMCrawlerOptions.additionalMimeTypes constructor option. Beware that the parsing behavior differs for HTML, XML, JSON and other types of content. For more details, see LinkeDOMCrawlerOptions.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 LinkeDOMCrawler constructor. For user convenience, the minConcurrency and maxConcurrency AutoscaledPool options are available directly in the LinkeDOMCrawler constructor.

Example usage

const crawler = new LinkeDOMCrawler({
    async requestHandler({ request, window }) {
        await Dataset.pushData({
            url: request.url,
            title: window.document.title,
        });
    },
});

await crawler.run([
    'http://crawlee.dev',
]);