<script>
       function checkBrowser() {
         
           // Get the user-agent string
           let userAgentString = 
               navigator.userAgent;
         
           // Detect Chrome
           let chromeAgent = 
               userAgentString.indexOf("Chrome") > -1;
         
           // Detect Internet Explorer
           let IExplorerAgent = 
               userAgentString.indexOf("MSIE") > -1 || 
               userAgentString.indexOf("rv:") > -1;
         
           // Detect Firefox
           let firefoxAgent = 
               userAgentString.indexOf("Firefox") > -1;
         
           // Detect Safari
           let safariAgent = 
               userAgentString.indexOf("Safari") > -1;
                 
           // Discard Safari since it also matches Chrome
           if ((chromeAgent) && (safariAgent)) 
               safariAgent = false;
         
           // Detect Opera
           let operaAgent = 
               userAgentString.indexOf("OP") > -1;
                 
           // Discard Chrome since it also matches Opera     
           if ((chromeAgent) && (operaAgent)) 
               chromeAgent = false;
         
           document.querySelector(".output-safari").textContent
                       = safariAgent;
           document.querySelector(".output-chrome").textContent
                       = chromeAgent;
           document.querySelector(".output-ie").textContent
                       = IExplorerAgent;
           document.querySelector(".output-opera").textContent
                       = operaAgent;
           document.querySelector(".output-firefox").textContent
                       = firefoxAgent;
       }
   </script>