AltLeft key code — keyCode 18

In code

Comparing against code keeps working when the layout changes.

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

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

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.