goog.events.KeyCodes

Returns true if the key fires a keypress event in the current browser.

Accoridng to MSDN [1] IE only fires keypress events for the following keys:

• Letters: A - Z (uppercase and lowercase)
• Numerals: 0 - 9
• Symbols: ! @ # $ % ^ & * ( ) _ - + = < [ ] { } , . / ? \ | ' ` " ~
• System: ESC, SPACEBAR, ENTER

That's not entirely correct though, for instance there's no distinction between upper and lower case letters.

[1] http://msdn2.microsoft.com/en-us/library/ms536939(VS.85).aspx)

Safari is similar to IE, but does not fire keypress for ESC.

Additionally, IE6 does not fire keydown or keypress events for letters when the control or alt keys are held down and the shift key is not. IE7 does fire keydown in these cases, though, but not keypress.

Returns true if the key produces a character. This does not cover characters on non-US keyboards (Russian, Hebrew, etc.).

Returns false if the event does not contain a text modifying key.

When it returns true, the event might be text modifying. It is infeasible to say for sure because of the many different keyboard layouts, so this method errs on the side of assuming a key event is text-modifiable if we cannot be certain it is not. As an example, it will return true for ctrl+a, though in many standard keyboard layouts that key combination would mean "select all", and not actually modify the text.

Normalizes key codes from their Gecko-specific value to the general one.

Normalizes key codes from OS/Browser-specific value to the general one.

Normalizes key codes from their Mac WebKit-specific value to the general one.