JS读取UserAgent信息并做判断

<script type="text/javascript">
    document.writeln("navigator.userAgent: " + navigator.userAgent + "<br />");
    document.writeln("navigator.appName: " + navigator.appName + "<br />");
    document.writeln("navigator.appCodeName: " + navigator.appCodeName + "<br />");
    document.writeln("navigator.appVersion: " + navigator.appVersion + "<br />");
    document.writeln("navigator.appMinorVersion: " + navigator.appMinorVersion + "<br />");
    document.writeln("navigator.platform: " + navigator.platform + "<br />");
    document.writeln("navigator.cookieEnabled: " + navigator.cookieEnabled + "<br />");
    document.writeln("navigator.onLine: " + navigator.onLine + "<br />");
    document.writeln("navigator.userLanguage: " + navigator.userLanguage + "<br />");
    document.writeln("navigator.mimeTypes[1].description: " + navigator.mimeTypes[1].description + "<br />");
    document.writeln("navigator.mimeTypes[1].type: " + navigator.mimeTypes[1].type + "<br />");
    document.writeln("navigator.plugins[3].description: " + navigator.plugins[3].description + "<br />");
</script>

<script type="text/javascript">
   var useHTML5 = 1;
   if(navigator.userAgent.indexOf("iPhone OS 4_0_2") !=-1)
   {
      useHTML5=2;
   }
   document.write("Value is: <br>");
   document.write(useHTML5);
</script>