New post! Web Scraping with #Javascript and #NodeJs.
Learn how to build a web scraper, add anti-blocking techniques, a headless browser, and parallelize requests with a queue.
zenrows.com/blog/web-scrap…
Learn how to build a web scraper, add anti-blocking techniques, a headless browser, and parallelize requests with a queue.
zenrows.com/blog/web-scrap…
You'll first build a web scraper using Axios and Cheerio, then a headless browser - Playwright.
Start by getting the HTML and parsing the content for new links to follow, applying Cheerio and CSS Selectors. Extract also content similarly.
Start by getting the HTML and parsing the content for new links to follow, applying Cheerio and CSS Selectors. Extract also content similarly.
Follow the gathered links and start a loop that will iterate over all links we find.
To avoid problems, set a maximum limit and store a list with the already visited URLs to prevent duplicates.
To avoid problems, set a maximum limit and store a list with the already visited URLs to prevent duplicates.
Next, a couple of techniques to avoid blocks, captchas, and so on: adding proxies and full-set headers.
As said earlier, we can move from Axios to Playwright to load Javascript or async content.
We can do that easily with a function for each and a boolean to switch them.
We can do that easily with a function for each and a boolean to switch them.
And lastly, we'll extract the full potential to Javascript: parallel calls.
By creating a queue, we can start crawling every URL we find without needing the previous one to finish.
By creating a queue, we can start crawling every URL we find without needing the previous one to finish.
Parallelization has its own problems, the main one being too many calls to process. To avoid that, we set a concurrency limit.
Meaning that no more than four calls will be running at any given time.
Meaning that no more than four calls will be running at any given time.
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