var IS_MAC = /Mac/.test(navigator.userAgent);

var KEY_A = 65;
var KEY_COMMA = 188;
var KEY_RETURN = 13;
var KEY_ESC = 27;
var KEY_LEFT = 37;
var KEY_UP = 38;
var KEY_P = 80;
var KEY_RIGHT = 39;
var KEY_DOWN = 40;
var KEY_N = 78;
var KEY_BACKSPACE = 8;
var KEY_DELETE = 46;
var KEY_SHIFT = 16;
var KEY_CMD = IS_MAC ? 91 : 17;
var KEY_CTRL = IS_MAC ? 18 : 17;
var KEY_TAB = 9;

var TAG_SELECT = 1;
var TAG_INPUT = 2;

// for now, android support in general is too spotty to support validity
var SUPPORTS_VALIDITY_API = !/android/i.test(window.navigator.userAgent) && !!document.createElement('form').validity;