KeyboardEvent Value (keyCodes, metaKey, etc)

When a KeyboardEvent fires, you can test which key was pressed because that event contains information you can write logic against.

document.addEventListener("keydown", function(event) {
  console.log(event.which);
})

For example, by pressing a, you’ll get 65. Apparently it’s best to write logic against which, as keyCode and charCode are complicated:

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The event.which property normalizes event.keyCode and event.charCode. It is recommended to watch event.which for keyboard key input.

And:

In a keypress event, the Unicode value of the key pressed is stored in either the keyCode or charCode property, never both. If the key pressed generates a character (e.g. ‘a’), charCode is set to the code of that character, respecting the letter case. (i.e. charCode takes into account whether the Shift key is held down). Otherwise, the code of the pressed key is stored in keyCode.

Tester Tool

Keycode values

Here’s a table that contains the values from event.which.

Zell Liew noticed that 3 of these keycodes were different in Firefox than the rest of the browsers

• ; is 59 in Firefox but 186 in other browsers.
• = is 61 in Firefox but 187 in other browsers.
• - is 173 in Firefox but 189 in other browsers.

These keycode values are only valid during in keydown and keyup events. On Mac, keypress events give you an completely different set of codes. For example:

Key	event.which in keydown	event.which in keypress
a	65	97
b	66	98
c	67	99