JS Chromebook Check If Chrome Is Running

<script language=javascript>
var Str
Str=(navigator.userAgent);
var len=Str.length;
var rep=Str.replace('Mozilla/5.0 (X11; CrOS x86_64 8350.68.0) AppleWebKit/537.36 (KHTML, like Gecko) ','');
var rep1=rep.replace('52.0.2743.116 Safari/537.36','');
document.write(rep1);
if(rep1=='Chrome/'){
alert('Chrome Detected!!');
}
else{
alert('Chrome Not Detected!!');
}
</script>