Detect Internet Explorer

/**
 * detect IE
 * returns version of IE or false, if browser is not Internet Explorer
 */
function detectIE() {
  var ua = window.navigator.userAgent;
 
  // Test values; Uncomment to check result …
 
  // IE 10
  // ua = 'Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)';
 
  // IE 11
  // ua = 'Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko';
 
  // Edge 12 (Spartan)
  // ua = 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36 Edge/12.0';
 
  // Edge 13
  // ua = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2486.0 Safari/537.36 Edge/13.10586';
 
  var msie = ua.indexOf('MSIE ');
  if (msie > 0) {
    // IE 10 or older => return version number
    return parseInt(ua.substring(msie + 5, ua.indexOf('.', msie)), 10);
  }
 
  var trident = ua.indexOf('Trident/');
  if (trident > 0) {
    // IE 11 => return version number
    var rv = ua.indexOf('rv:');
    return parseInt(ua.substring(rv + 3, ua.indexOf('.', rv)), 10);
  }
 
  var edge = ua.indexOf('Edge/');
  if (edge > 0) {
    // Edge (IE 12+) => return version number
    return parseInt(ua.substring(edge + 5, ua.indexOf('.', edge)), 10);
  }
 
  // other browser
  return false;
}

// Get IE or Edge browser version
var version = detectIE();
 
if (version === false) {
  document.getElementById('result').innerHTML = '<s>IE/Edge</s>';
} else if (version >= 12) {
  document.getElementById('result').innerHTML = 'Edge ' + version;
} else {
  document.getElementById('result').innerHTML = 'IE ' + version;
}
 
// add details to debug result
document.getElementById('details').innerHTML = window.navigator.userAgent;