if (navigator.appVersion.indexOf("Mac")!=-1) OSName="MacOS";

var v = navigator.userAgent.match(/Mac OS X ([d_]+)/)
if(v!=null && v[1] == "10_8_2") {
    alert("U r not support!");
}

var macVersion = navigator.userAgent.match(/Mac OS X ([0-9.]+)/i)[1],
    versionNames = { '10.0': 'Cheetah', '10.1': 'Puma', '10.2': 'Jaguar', '10.3': 'Panther', '10.4': 'Tiger', '10.5': 'Leopard', '10.6': 'Snow Leopard', '10.7': 'Lion', '10.8': 'Mountain Lion' };

if(typeof versionNames[macVersion] !== 'undefined')
{
    alert(versionNames[macVersion]);
}

navigator.platform