How to detect Alt / Option
document.addEventListener('keydown', (event) => {
if (event.key === 'Alt') {
// Alt / Option was pressed
}
});Use event.key to react to what the key means (it follows the keyboard layout) and event.code for its physical position, for example WASD in games. keyCode and which are deprecated: they still work, but their values differ between browsers and layouts.
How browsers treat Alt / Option
Check event.altKey. On many European keyboards the right Alt key is AltGr (event.key === "AltGraph") and types characters such as @ or €, so avoid Ctrl+Alt shortcuts that clash with it. On a Mac, Option changes event.key to special characters — use event.code for Option shortcuts.
In React
<input onKeyDown={(e) => { if (e.key === 'Alt') { /* … */ } }} />JavaScript Keycode FinderPress any key and instantly see every property of the keyboard event, with a copy-ready keydown snippet for shortcuts.
Open the tool Frequently asked questions
What is the keyCode for Alt / Option?
18. It’s deprecated, though: use event.key (“Alt”) or event.code (AltLeft) in new code.
What is the difference between event.key and event.code?
event.key is the character or action the key produces with the current layout; event.code is the physical key position, the same on every layout.
Should I use keydown or keypress?
keydown. The keypress event is deprecated and doesn’t fire for keys that don’t produce characters, such as Escape or the arrow keys.