Getting the keycode from keyboard events

Binding an event handler to keyboard actions and retrieving the keycode that triggered the event.

To get the key code, attaching an event handler to any keyboard action is required. The key code is reported on the event object received by the handler function.

// event handler function
function handler(e) {
var key = window.event ? e.keyCode : e.which;
console.log(key, e.shiftKey, e.altKey, e.ctrlKey);

// attach handler to the keydown event of the document
if (document.attachEvent) document.attachEvent('onkeydown', handler);
else document.addEventListener('keydown', handler);

It's possible to use any of the keyboard events (keypress, keydown, keyup) on DOM elements, such as text input fields or textareas.