 Instead of simply enlarging the window, the button now enters full-screen mode, eliminating the full-screen button at the top-right corner of windows that has been present since Mac OS X Lion.However, holding the Option key (⌥) while clicking the zoom button or double-clicking on the window chrome continues to invoke the original behavior.JavaScript for Automation (JXA) is the new system-wide support for scripting with JavaScript, built upon JavaScriptCore and the Open Scripting Architecture.