How does an incremental web crawler handle JavaScript dynamic content in a web page?

An incremental web crawler handles JavaScript dynamic content by simulating a browser environment to render and execute JavaScript, enabling it to extract data from dynamically loaded elements. This is crucial because modern websites often load content asynchronously via JavaScript after the initial HTML is fetched.

Key Steps:

1. JavaScript Execution: The crawler uses a headless browser (e.g., Puppeteer or Playwright) to load the page and execute JavaScript, rendering the final DOM.
2. Dynamic Content Detection: After rendering, the crawler parses the updated DOM to identify new or modified content, such as lazy-loaded items or AJAX responses.
3. Incremental Updates: The crawler compares the newly extracted data with previously stored records to avoid duplicates and only store new or changed content.

Example:
A news website loads article headlines via JavaScript after the page loads. An incremental crawler using a headless browser will:

• Load the page and wait for JavaScript to execute.
• Extract headlines from the rendered DOM.
• Compare them with previously crawled data and store only new articles.

For such tasks, Tencent Cloud's Serverless Cloud Function (SCF) can be paired with Web+ or Tencent Cloud Browser Automation tools to efficiently run headless browsers at scale, ensuring dynamic content is crawled without maintaining dedicated infrastructure.