Get Link Extension

function getLinkExtension(url) {
  try {
    const path = new URL(url).pathname;
    const lastSegment = path.split("/").pop();
    return lastSegment.includes(".")
      ? lastSegment.split(".").pop().toLowerCase()
      : null;
  } catch {
    return null;
  }
}

getLinkExtension("https://example.com/file.pdf"); // "pdf"
getLinkExtension("https://example.com/archive.tar.gz"); // "gz"(note how only the last extension is returned)
getLinkExtension("https://example.com/video.mp4?download=true"); // "mp4"
getLinkExtension("https://example.com/folder/"); // null (no file in the URL)
getLinkExtension("invalid-url"); // null (invalid URL)