Internet Explorer 11 detection vanillajs (IE11)

ie11.js

// IE 11 detection
// put it in head as first script, otherwise js errors won't prevent execution
// thanks to https://stackoverflow.com/a/65446599/809939

var ua = window.navigator.userAgent;
var trident = ua.indexOf('Trident/');
if (trident > 0) {
  var rv = ua.indexOf('rv:');

  console.log("Detected IE " + parseInt(ua.substring(rv + 3, ua.indexOf('.', rv)), 10));
  
  // A) redirect - OR
  window.location.href = "https://mywebsitexzy.org/ie11.html";

  // B) info notice
  /*document.addEventListener("DOMContentLoaded", function(event) {
    //console.log('IE11, DOMContentLoaded');
    // add warning
    var infoText = document.createElement("p");
    infoText.innerHTML = '<div class="ie11-info-message"><p>Vielen Dank für Ihren Besuch!</p>'+
    '<p>Der Browser "Internet Explorer 11" wird von unserer Webseite nicht unterstützt.</p>'+
    '<p>Bitte benutzen Sie einen aktuellen Web-Browser.</p></div>';
    document.body.insertBefore(infoText, document.body.childNodes[0]);
    
  });*/
}