The KeyboardEvent.code property represents a physical key on the keyboard (as opposed to the character generated by pressing the key). In other words, this property returns a value that isn't altered by keyboard layout or the state of the modifier keys.

If the input device isn't a physical keyboard, but is instead a virtual keyboard or accessibility device, the returned value will be set by the browser to match as closely as possible to what would happen with a physical keyboard, to maximize compatibility between physical and virtual input devices.

This property is useful when you want to handle keys based on their physical positions on the input device rather than the characters associated with those keys; this is especially common when writing code to handle input for games that simulate a gamepad-like environment using keys on the keyboard. Be aware, however, that you can't use the value reported by KeyboardEvent.code to determine the character generated by the keystroke, because the keycode's name may not match the actual character that's printed on the key or that's generated by the computer when the key is pressed.

For example, the code returned is "KeyQ" for the Q key on a QWERTY layout keyboard, but the same code value also represents the ' key on Dvorak keyboards and the A key on AZERTY keyboards. That makes it impossible to use the value of code to determine what the name of the key is to users if they're not using an anticipated keyboard layout.

To determine what character corresponds with the key event, use the KeyboardEvent.key property instead.

Specifies some detail information about the Event, depending on the type of event. The un-initialized value of this attribute must be 0.

The KeyboardEvent interface's key read-only property returns the value of the key pressed by the user, taking into consideration the state of modifier keys such as Shift as well as the keyboard locale and layout. 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".
• 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.

If you want to access the event properties in an asynchronous way, call this on the event, which will remove the synthetic event from the pool and allow references to the event to be retained by user code.

Stops the default action of an element from happening. For example: Prevent a submit button from submitting a form Prevent a link from following the URL

Stops the bubbling of an event to parent elements, preventing any parent event handlers from being executed.

The view attribute identifies the AbstractView from which the event was generated. The un-initialized value of this attribute must be null.