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Aman Gupta
Aman Gupta

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How does a web scraper work?

Recently I made a web scraper for my EEG attention classification project, here's how a web scraper works.

1. Request:

  • The web scraper starts by receiving a request from the user specifying the target website and desired data.
  • The request may also include specific instructions for filtering or parsing the extracted information.

2. Fetching Data:

  • The scraper initiates a web request to the target website, mimicking a regular browser visit.
  • This request retrieves the website's HTML code, which contains all the content and structure information.

3. Parsing the HTML:

  • The scraper then parses the downloaded HTML code using various techniques like regular expressions or dedicated libraries.
  • This process identifies and extracts the desired data based on the provided instructions.

4. Data Extraction:

  • The extracted data can be targeted specific elements like text within specific HTML tags or attributes.
  • Alternatively, the scraper can extract entire sections or tables based on their structure and position.

5. Handling Dynamic Content:

  • Some websites use dynamic content generated by JavaScript or other scripting languages.
  • Web scrapers often utilise headless browsers or dedicated libraries to handle such dynamic content and extract the relevant data.

6. Data Processing:

  • Once extracted, the data can be cleaned, formatted, and converted to the desired format (e.g., CSV, JSON).
  • This may involve removing unwanted elements, handling inconsistencies, and structuring the data for further use.

7. Storage and Output:

  • Finally, the processed data is stored in a chosen location (e.g., local file, database) or delivered to the user.
  • The output format and delivery method depend on the specific application and user needs.

Additional Points:

  • Web scrapers can be automated to run periodically and collect updated data over time.
  • Advanced scrapers can handle complex website structures and utilise various techniques to avoid detection and bypass anti-scraping measures.
  • Ethical web scraping practices involve respecting robots.txt guidelines and using responsible scraping techniques.


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