Is it possible to extract information from a string that includes HTML code within a browser using CSS selectors without actually generating the DOM elements?

I've been struggling with this basic task for hours. I can't find any libraries that work and none of the questions here address my specific issue.

Here's what I need to do:

  • The entire page's markup is in a string format.
  • I must use CSS selectors to target the elements I want to extract data from.
  • I don't want to create actual HTML DOM elements, just scrape data. The page may contain images, audio, video, and other elements that I'm not interested in creating.
  • It needs to handle markup errors and follow HTML5-style tagging. Trying to parse it as XML throws an "Invalid XML" error.
  • This operation must happen in the browser without using NodeJS modules.

In Java, I achieved this using JSoup. However, I haven't found a comparable library for JavaScript in the browser.

Thank you for your assistance.

javascriptcssxml-parsingweb-scrapinghtml-parsing

Answer №1

Following @JaromandaX's advice proved to be successful. Using a DOMParser object is an effective method for achieving this task. It enables the creation of elements and permits the utilization of .querySelector or .querySelectorAll on them without loading external resources or executing any scripts.

Here is the solution that solved my issue:

var parser = new DOMParser();
var doc = parser.parseFromString(htmlString, "text/html");

Answer №2

If you're looking to scrape websites, you have a couple of options like using PHP Goutte or Python's BeautifulSoup4 library. Both libraries allow you to utilize CSS Selectors or XPaths based on your preference.

Below are some basic examples to help you get started:

Using PHP Goutte:

require_once 'vendor/autoload.php';
use Goutte\Client;

$client = new Client();
$resp = $client->request('GET', $url);
foreach ($resp->filter(' your css selector here') as $li) {
// your logic here
}

Example with Python BeautifulSoup:

import requests
from bs4 import BeautifulSoup
timeout_time = 30;

def tryAgain(passed_url):
    # A sample function for making multiple attempts at scraping a URL
    # Add your own custom headers here 
    pass

header = [{"User-Agent": "Mozilla/5.0 (Windows NT 5.1; rv:14.0) Gecko/20100101 Firefox/14.0.1"},
{"User-Agent":"Opera/9.80 (Windows NT 6.0) Presto/2.12.388 Version/12.14"},
{"User-Agent":"Mozilla/5.0 (Windows; U; Windows NT 6.1; rv:2.2) Gecko/20110201"},
{"User-Agent":"Mozilla/5.0 (iPad; CPU OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5355d Safari/8536.25"}]

main_url = " your URL here "

main_page_html  = tryAgain(main_url)
main_page_soup = BeautifulSoup(main_page_html, "html.parser")

for a in main_page_soup.select(' css selector here '):
        print a.select(' your css selector here ')[0].text

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