Kanna is a Swift library for parsing XML and HTML. It allows you to apply XPath, CSS, and Swift-style query syntax to extract data from HTML/XML documents, which is useful for web scraping static content. However, when it comes to web scraping, it's important to distinguish between static and dynamic content:
Static content is that which is served directly by the web server as it is, typically in the form of HTML, CSS, and static JavaScript files. The content doesn't change unless the page is updated by the webmaster.
Dynamic content, on the other hand, is generated on-the-fly by client-side JavaScript or through AJAX requests after the initial page load. This content is not present in the initial HTML source and thus cannot be directly scraped using standard HTML parsing libraries like Kanna.
So, to answer your question:
Yes: You can use Kanna for extracting static content. This is because the content is embedded directly in the initial HTML document, which can be fetched with an HTTP request and then parsed with Kanna.
No: Kanna by itself is not designed to handle dynamic content that is loaded asynchronously via JavaScript or through API requests. For dynamic content, you would typically need to use a headless browser or web automation tool that can render JavaScript and allow you to interact with the page as a user might.
For dynamic content, you might use tools such as Selenium, Puppeteer (for Node.js), or Playwright. These tools can programmatically control a web browser, allowing you to scrape content that is loaded dynamically.
Here's a basic example of how you would use Kanna in Swift to scrape static content:
import Foundation
import Kanna
let html = "<html><body><p>Hello, World!</p></body></html>"
if let doc = try? HTML(html: html, encoding: .utf8) {
for p in doc.xpath("//p") {
print(p.text ?? "")
}
}
For dynamic content, you might use Puppeteer in JavaScript:
const puppeteer = require('puppeteer');
async function scrapeDynamicContent(url) {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto(url);
// You might need to wait for a selector that indicates that the content has loaded
await page.waitForSelector('selector-for-dynamic-content');
const dynamicContent = await page.evaluate(() => {
// Extract the dynamic content using DOM manipulation
return document.querySelector('selector-for-dynamic-content').innerText;
});
console.log(dynamicContent);
await browser.close();
}
scrapeDynamicContent('http://example.com');
Remember, when scraping websites, whether for static or dynamic content, you should always check the website's robots.txt file and terms of service to ensure that you're allowed to scrape their data, and you should scrape responsibly to avoid overloading their servers.
