JSFiddle - React, Tailwind, and code Playground

HTML

<div id="output">

</div>

JavaScript

function _getInternetExplorerVersion() {
  let rv = -1;

  if(navigator.appName === 'Microsoft Internet Explorer') {
    let re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");

    if(re.exec(navigator.userAgent) !== null){
      rv = parseFloat( RegExp.$1 );
    }
  }
  else if(navigator.appName === 'Netscape') {
    let re = new RegExp("Trident/.*rv:([0-9]{1,}[\.0-9]{0,})");

    if(re.exec(navigator.userAgent) !== null) {
      rv = parseFloat(RegExp.$1);
    }
  }

  return rv;
}

  function isWindows7IE11(){
    return (_getInternetExplorerVersion() === 11) && (navigator.appVersion.indexOf("Windows NT 6.1") !== -1);
  }

var div = document.getElementById("output");
if (isWindows7IE11()){
	div.innerHTML = "Windows 7 IE 11";
}else{
	div.innerHTML = "Not windows 7, IE 11";
}