var matchesOSPrefix = function(prefix) {
  var pre = prefix.toLowerCase();
  var platform = window.navigator.platform.toLowerCase();
  return platform.indexOf(pre) === 0;
};

var windows = function() {
  return matchesOSPrefix('Win');
};

var mac = function() {
  return matchesOSPrefix('Mac') || matchesOSPrefix('iP');
};

if (windows()) {
  // Display PS Command
  console.log('Windows');
} else if (mac()) {
  // Display  OSX Command (curl)
  console.log('Mac');
} else {
  // Display Linux Command (curl, wget?)
  console.log('Linux');
}