node-webkit window.isFocused emulation

is-focused.js

(function() {
  window.frame = require("nw.gui").Window.get();
  window.frame.isFocused = true;

  var windowFocusHandler = function() {
      window.frame.isFocused = true;
    }
    , windowBlurHandler = function() {
      window.frame.isFocused = false;
    }
  ;

  window.frame.on("focus", windowFocusHandler);
  window.frame.on("blur", windowBlurHandler);
  window.addEventListener("focus", windowFocusHandler);
  window.addEventListener("blur", windowBlurHandler);
})();