Js determines the type of browser to run the JSP page and the version sample

In the past two days, I made a business of determining the browser type and version number, and recorded the js code:

 
function allinfo(){ 

var ua = navigator.userAgent; 
ua = ua.toLowerCase(); 
var match = /(webkit)[ /]([w.]+)/.exec(ua) || 
/(opera)(?:.*version)?[ /]([w.]+)/.exec(ua) || 
/(msie) ([w.]+)/.exec(ua) || 
!/compatible/.test(ua) && /(mozilla)(?:.*? rv:([w.]+))?/.exec(ua) || []; 

//If you need to get the browser version number: match[2]

switch(match[1]){ 
case "msie": //ie 
if (parseInt(match[2]) === 6){ //ie6 
alert("ie6"); 
alert(" Temporarily not supported IE7.0 And the following version of the browser, please upgrade your browser version! "); 
//document.getElementById("hid").style.display = "none"; 
// document.getElementById("show").style.display = "block"; 
//document.getElementById("nosee_b").style.display = "none"; 
} 
else if (parseInt(match[2]) === 7) { //ie7 
alert("ie7"); 
//document.getElementById("hid").style.display = "none"; 
// document.getElementById("show").style.display = "block"; 
} 
else if (parseInt(match[2]) === 8){ //ie8 
alert("ie8"); 
} 
else if(parseInt(match[2]) === 9){ 
alert("ie9"); 
//document.getElementById("hid").style.display = "none"; 
} 
break; 
case "webkit": //safari or chrome 
//alert("safari or chrome"); 
// document.getElementById("middle").style.display = "none"; 
break; 
case "opera": //opera 
alert("opera"); 
break; 
case "mozilla": //Firefox 
alert("Firefox"); 
//document.getElementById("hid").style.display = "none"; 
break; 
default: 
break; 
} 
}