KeyboardEvent.key

The KeyboardEvent.key read-only property returns the value of a key or keys pressed by the user. Its value is determined as follows:

• If the pressed key has a printed representation, the returned value is a non-empty Unicode character string containing the printable representation of the key.
• If the pressed key is a control or special character, the returned value is one of the pre-defined key values.
• If the KeyboardEvent represents the press of a dead key, the key value must be "Dead".
• If more than one key is pressed and the combination includes a modifier that makes the resulting keystroke non printing, the returned value is the printable character. For example, if the combination were Control + a, the letter "a" is returned.
• Some specialty keyboard keys (such as the extended keys for controlling media on multimedia keyboards) don't generate key codes on Windows; instead, they trigger WM_APPCOMMAND events. These events get mapped to DOM keyboard events, and are listed among the "Virtual key codes" for Windows, even though they aren't actually key codes.
• If the key cannot be identified, the returned value is "Unidentified".

Example

This example uses EventTarget.addEventListener() to listen for keydown events. When they occur, the key's value is checked to see if it's one of the keys the code is interested in, and if it is, it gets processed in some way (possibly by steering a spacecraft, perhaps by changing the selected cell in a spreadsheet).

window.addEventListener("keydown", function (event) {
  if (event.defaultPrevented) {
    return; // Do nothing if the event was already processed
  }

  switch (event.key) {
    case "ArrowDown":
      // Do something for "down arrow" key press.
      break;
    case "ArrowUp":
      // Do something for "up arrow" key press.
      break;
    case "ArrowLeft":
      // Do something for "left arrow" key press.
      break;
    case "ArrowRight":
      // Do something for "right arrow" key press.
      break;
    case "Enter":
      // Do something for "enter" or "return" key press.
      break;
    case "Escape":
      // Do something for "esc" key press.
      break;
    default:
      return; // Quit when this doesn't handle the key event.
  }

  // Cancel the default action to avoid it being handled twice
  event.preventDefault();
}, true);

Specification

Browser compatibility

[1]: Internet Explorer's implementation does not completely match the current spec because it is based on an older version of the spec.