Can I use Scraper (Rust) for both static and dynamic content extraction?

Scraper is a web scraping library for Rust that is primarily designed for extracting data from static HTML content. It is built on top of select, a Rust library for extracting data from HTML/XML documents using CSS selectors. Since Scraper operates on static HTML, it is well-suited for parsing and extracting information from webpages that do not rely on JavaScript for content generation.

For static content extraction, Scraper works great. You can use it to download the HTML content of a page using an HTTP client like reqwest, then parse and select the relevant parts of the HTML document using Scraper's CSS selector functionality.

Here's a simple example of how you might use Scraper to extract data from static HTML content in Rust:

use reqwest;
use scraper::{Html, Selector};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Send a GET request
    let resp = reqwest::get("https://example.com").await?;
    let body = resp.text().await?;

    // Parse the HTML document
    let document = Html::parse_document(&body);

    // Create a CSS selector
    let selector = Selector::parse(".some-class").unwrap();

    // Iterate over elements matching the selector
    for element in document.select(&selector) {
        let text = element.text().collect::<Vec<_>>();
        println!("{:?}", text);
    }

    Ok(())
}

For dynamic content, which relies on JavaScript to build the webpage, Scraper alone is not sufficient, because it cannot execute JavaScript or wait for asynchronous operations to complete. Web pages that load content dynamically typically require a headless browser that can execute JavaScript and render the content as a user's browser would.

To scrape dynamic content in Rust, you can use a headless browser automation framework like fantoccini, which is a Rust library that controls a real web browser via the WebDriver protocol. fantoccini can interact with dynamic pages, wait for JavaScript execution, and then extract the content.

Here's how you might use fantoccini to extract data from a dynamically loaded web page:

use fantoccini::{Client, ClientBuilder};

#[tokio::main]
async fn main() -> Result<(), fantoccini::error::CmdError> {
    let client = ClientBuilder::native().connect("http://localhost:4444").await?;
    client.goto("https://example.com").await?;

    // Wait for an element to be present and visible
    let elem = client.wait_for_find(fantoccini::Locator::Css(".some-dynamic-class")).await?;

    // Get the text of the element
    let text = elem.text().await?;
    println!("{}", text);

    // You can also interact with the page, click buttons, fill out forms, etc.

    // Always remember to close the session
    client.close().await?;

    Ok(())
}

In the above example, you'll need to have a WebDriver-compatible browser automation tool like chromedriver or geckodriver running and listening on the specified port (localhost:4444 in this case).

To summarize, while Scraper is suited for static content extraction in Rust, for dynamic content you'll need to use a combination of a headless browser like fantoccini and potentially Scraper once the content has been rendered.