@crawlee/http

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 adjust gotOptions:

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

By default, HttpCrawler 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 HttpCrawlerOptions.additionalMimeTypes constructor option. Beware that the parsing behavior differs for HTML, XML, JSON and other types of content. For more 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 HttpCrawler constructor. For user convenience, the minConcurrency and maxConcurrency AutoscaledPool options are available directly in the HttpCrawler constructor.

Example usage

import { HttpCrawler, Dataset } from '@crawlee/http';

const crawler = new HttpCrawler({
    requestList,
    async requestHandler({ request, response, body, contentType }) {
        // Save the data to dataset.
        await Dataset.pushData({
            url: request.url,
            html: body,
        });
    },
});

await crawler.run([
    'http://www.example.com/page-1',
    'http://www.example.com/page-2',
]);