Undo key code — keyCode 0

Editing

Undo has keyCode 0 and key Undo, at location 0. It shares that number with Power, WakeUp, NumpadParenLeft, NumpadParenRight, Cut, Copy, Paste, Again, Find, Props, Fn.

Deleting, inserting, breaking a line.

code (position): Undo
key (US layout): Undo
keyCode (deprecated): 0
Hexadecimal: 0x00
location: 0 · Standard
Types a character: No
Shares keyCode with: Power, WakeUp, NumpadParenLeft, NumpadParenRight, Cut, Copy, Paste, Again, Find, Props, Fn

In code

Comparing against code keeps working when the layout changes.

window.addEventListener('keydown', e => {
  if (e.code === 'Undo') {
    // Undo
  }
});

code versus key

code is the physical position, the same on a Korean or French keyboard. key is what gets typed and changes — the same spot gives a, A or ㅁ. Use code to ask which spot was pressed, key to ask what was entered.

keyCode has been dropped from the standard. Write new code against code or key; the numbers here are for reading old code.

Keys of the same kind

Backspace Delete Insert Cut Copy Paste

How to read this

code is the position, key is the character typed. Match on code for shortcuts.
keyCode is deprecated; use it only to read old code.
Left and right Shift share a keyCode and are told apart by location.
The 1 on the number row and the 1 on the numpad are different keys — 49 and 97.

Frequently asked questions

Q. What is the keyCode for Undo?

0, or 0x00 in hexadecimal.

Q. How do I match Undo in code?

Compare with e.code === 'Undo'. Matching on keyCode wobbles between browsers and layouts.

Q. What is this key's location?

0. It shares a keyCode with Power, WakeUp, NumpadParenLeft, NumpadParenRight, Cut, Copy, Paste, Again, Find, Props, Fn, so you need this value to tell them apart.

Q. Does this key type a character?

No. key is Undo and nothing is entered.