Fetch URL to see if a link exists in given URL

script.js

function checkLink(url, domain) {
  try {
    var response = UrlFetchApp.fetch(url, {muteHttpExceptions: true});
    var content = response.getContentText();
    
    // Create a regular expression to match links to the specified domain
    var regex = new RegExp('href=["\']https?:\/\/(www\.)?' + domain.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'), 'i');
    
    // Check if the content contains a link matching the regex
    return regex.test(content);
  } catch (error) {
    // If there's an error (e.g., invalid URL), return false
    return false;
  }
}

function extractLinks(url, domain) {
  try {
    var response = UrlFetchApp.fetch(url, {muteHttpExceptions: true});
    var content = response.getContentText();
    
    // Escape special characters in the domain
    var escapedDomain = domain.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
    
    // Improved regex to match links more precisely
    var regex = new RegExp('<a\\s+(?:[^>]*?\\s+)?href=(["\'])(https?:\\/\\/(?:www\\.)?' + escapedDomain + '(?:\\/[^"\']*)?)?\\1[^>]*>.*?<\\/a>', 'gi');
    
    var matches = content.match(regex);
    
    if (matches) {
      // Filter out any matches that don't actually contain the domain
      matches = matches.filter(function(match) {
        return match.includes(domain);
      });
      return matches.join('\n');
    } else {
      return '';
    }
  } catch (error) {
    return '';
  }
}