js method to detect browser version

function check(){
        var browser=navigator.appName
        var b_version=navigator.appVersion
        var version=b_version.split(";");
        var trim_Version=version[1].replace(/[ ]/g,"");
        if(browser=="Microsoft Internet Explorer" && trim_Version=="MSIE10.0")
 
        {
            alert("IE 10.0");
        }
            else if(browser=="Microsoft Internet Explorer" && trim_Version=="MSIE6.0")
        {
            alert("IE 6.0");
        }
    }