function isChromium() {
  //return navigator.userAgentData && navigator.userAgentData.brands.some(data => data.brand == 'Chromium');
  return typeof chrome !== 'undefined';
}

if (! isChromium()) {
  document.querySelectorAll("button").forEach((e) => {
    if (e.innerText == "HT J2K") e.disabled = true;
  });
}

function load_pdf(iframe_id, pdf_uri, callback) {
    const xhr = new XMLHttpRequest();
    const pdfFrame = document.getElementById(iframe_id); 
    const btn = this;
    btn.disabled = true;
    pdfFrame.src = "data:text/html,Fetching";
    xhr.onload = function () {
      pdfFrame.onload = () => btn.disabled = false;
      pdfFrame.src = URL.createObjectURL(xhr.response);
    }
    xhr.responseType = "blob";
    xhr.onerror = (ev) =>  console.log(ev);
    xhr.open('GET', pdf_uri);
    xhr.send(null);
};