This JavaScript snippet is used to show all the domains a website is using. This is helpful when maintaining a proxy server with whitelisting domains. All the code is taken from ChatGPT. You can add this as snippet in Chrome -> Developer Tools -> Sources (tab) -> Snippets (sub tab)

GetDomains.js

(function() {
    let domains = new Set();

    // Collect all resource URLs from the performance API
    performance.getEntriesByType("resource").forEach((entry) => {
        let url = new URL(entry.name);
        domains.add(url.hostname);
    });

    // Helper function to add a URL's hostname to the set
    function addDomainFromUrl(url) {
        try {
            let parsedUrl = new URL(url);
            domains.add(parsedUrl.hostname);
        } catch (e) {
            console.error(`Invalid URL: ${url}`);
        }
    }

    // Collect URLs from hyperlinks and form actions
    document.querySelectorAll('a[href], form[action], iframe[src]').forEach((element) => {
        let url;
        if (element.tagName === 'A') {
            url = element.href;
        } else if (element.tagName === 'FORM') {
            url = element.action;
        } else if (element.tagName === 'IFRAME') {
            url = element.src;
        }
        if (url) {
            addDomainFromUrl(url);
        }
    });

    // Collect URLs from inline styles (e.g., background images)
    document.querySelectorAll('[style]').forEach((element) => {
        let style = element.style.backgroundImage || element.style.background || element.style.content;
        let matches = style.match(/url\((['"]?)(.*?)\1\)/);
        if (matches && matches[2]) {
            addDomainFromUrl(matches[2]);
        }
    });

    // Convert Set to array
    let domainsArray = [...domains];

    // Function to sort domains with fewer parts (likely top-level domains) first
    function sortDomains(a, b) {
        // Compare based on the number of parts in the domain name
        return a.split('.').length - b.split('.').length;
    }

    // Sort domains
    domainsArray.sort(sortDomains);

    // Generate a filename based on the website's main domain
    function getBaseDomain(url) {
        try {
            let parsedUrl = new URL(url);
            return parsedUrl.hostname;
        } catch (e) {
            console.error(`Invalid URL for base domain: ${url}`);
            return 'website';
        }
    }

    // Get the base domain from the current page URL
    let baseDomain = getBaseDomain(window.location.href);
    let sanitizedBaseDomain = baseDomain.replace(/[^a-zA-Z0-9]/g, '_'); // Sanitize filename
    let filename = `${sanitizedBaseDomain}_domains.txt`;

    // Convert sorted array to a text format
    let domainsText = domainsArray.join('\n');

    // Create a Blob from the domains text
    let blob = new Blob([domainsText], { type: 'text/plain' });

    // Create a link element
    let link = document.createElement('a');

    // Set the download attribute with the dynamic filename
    link.download = filename;

    // Create a URL for the Blob and set it as the href attribute
    link.href = URL.createObjectURL(blob);

    // Append the link to the body
    document.body.appendChild(link);

    // Programmatically click the link to trigger the download
    link.click();

    // Remove the link from the document
    document.body.removeChild(link);

    // Log the sorted domains to console
    console.log("Sorted Domains:", domainsArray);
})();