function extractKeyCode(e) {
        if (e.charCode) {
            // "keypress" events mostly
            var char = String.fromCharCode(e.charCode).toUpperCase();
            return keyCodes_1.KeyCodeUtils.fromString(char);
        }
        return KEY_CODE_MAP[e.keyCode] || 0 /* Unknown */;
    }
https://lists.w3.org/Archives/Public/www-dom/2010JulSep/att-0182/keyCode-spec.html
If an Input Method Editor is processing key input and the event is keydown, return 229.