How do I use Simple HTML DOM to scrape AJAX-loaded content?

Simple HTML DOM is a PHP library that makes it easy to manipulate HTML elements. However, it works with static HTML content that you fetch from websites. When you deal with AJAX-loaded content, the content is dynamically loaded by JavaScript after the initial page load, which means that the content you're interested in might not be present in the HTML at the time you fetch it with your PHP script.

To scrape AJAX-loaded content using PHP, you have to simulate the AJAX requests that the browser would make to fetch the content or use a headless browser that can execute JavaScript and wait for the AJAX requests to complete before scraping the content. Below are two approaches to handle AJAX-loaded content for web scraping.

Approach 1: Simulate AJAX Requests

1. Inspect the network traffic on the page that loads the content via AJAX to find the exact request that fetches the content.
2. Replicate the request in your PHP script to directly fetch the data from the server.

Here's how you might do this using PHP's cURL:

<?php
// Initialize the cURL session
$ch = curl_init();

// Set the URL of the AJAX request
curl_setopt($ch, CURLOPT_URL, 'https://example.com/ajax-endpoint');
// Set the HTTP method and any necessary headers
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'X-Requested-With: XMLHttpRequest',
    // Include other headers as necessary
]);

// Return the response instead of printing it
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// Execute the cURL request
$response = curl_exec($ch);

// Check for errors
if (curl_errno($ch)) {
    throw new Exception(curl_error($ch));
}

// Close the cURL session
curl_close($ch);

// Now you can parse the $response using Simple HTML DOM or other methods

?>

Make sure to adjust the CURLOPT_URL, CURLOPT_CUSTOMREQUEST, and CURLOPT_HTTPHEADER options to match the AJAX request you are trying to simulate.

Approach 2: Use a Headless Browser

A headless browser can execute JavaScript and wait for AJAX requests to complete before scraping the content. Tools like Puppeteer (for Node.js) or Selenium can be used for this purpose.

Here is an example using Puppeteer with Node.js:

const puppeteer = require('puppeteer');

(async () => {
    // Launch a headless browser
    const browser = await puppeteer.launch();
    const page = await browser.newPage();

    // Navigate to the page
    await page.goto('https://example.com', { waitUntil: 'networkidle0' });

    // Now the AJAX content should be loaded, you can scrape it
    const content = await page.content();

    // You can use page.evaluate to extract data from the page
    const data = await page.evaluate(() => {
        // Access DOM elements and extract data
        const title = document.querySelector('h1').innerText;
        return { title };
    });

    console.log(data);

    // Close the browser
    await browser.close();
})();

You would need to have Node.js and Puppeteer installed to run this code. Install Puppeteer with npm:

npm install puppeteer

Note that using a headless browser is much heavier in terms of resources than a simple HTTP request. It is best used when no other option is available or when the page relies heavily on JavaScript to construct the DOM.

Simple HTML DOM can then be used to parse the static HTML content that you've retrieved using either of the two approaches. If you've fetched JSON or XML data from an AJAX endpoint, you'll need to use the appropriate PHP functions (like json_decode for JSON) to parse the data.