objects that inherit their interaction model from the InteractiveObject class
can respond to keyboard events by using event listeners. For example,
you can place an event listener on the Stage to listen for and respond
to keyboard input. In the following code, an event listener captures
a key press, and the key name and key code properties are displayed:
trace("Key Pressed: " + String.fromCharCode(event.charCode) + " (character code: " + event.charCode + ")");
Some keys, such as the Ctrl key, generate events even though
they have no glyph representation.
In the previous code example, the keyboard event listener captured
keyboard input for the entire Stage. You can also write an event
listener for a specific display object on the Stage; this event
listener is triggered when the object has the focus.
In the following example, keystrokes are reflected in the Output
panel only when the user types inside the TextField instance. Holding
the Shift key down temporarily changes the border color of the TextField
This code assumes there is a TextField instance named tf on
tf.border = true;
tf.type = "input";
trace("Key Pressed: " + String.fromCharCode(event.charCode) + " (key code: " + event.keyCode + " character code: " + event.charCode + ")");
if (event.keyCode == Keyboard.SHIFT) tf.borderColor = 0xFF0000;
trace("Key Released: " + String.fromCharCode(event.charCode) + " (key code: " + event.keyCode + " character code: " + event.charCode + ")");
if (event.keyCode == Keyboard.SHIFT)
tf.borderColor = 0x000000;
The TextField class also reports a textInput event
that you can listen for when a user enters text. For more information,
see Capturing text input.
Note: In the AIR runtime, a keyboard event can be canceled. In the
Flash Player runtime, a keyboard event cannot be canceled.
Key codes and character codes
You can access the keyCode and charCode properties
of a keyboard event to determine what key was pressed and then trigger
other actions. The keyCode property is a numeric
value that corresponds to the value of a key on the keyboard. The charCode property
is the numeric value of that key in the current character set. (The
default character set is UTF-8, which supports ASCII.)
The primary difference between the key code
and character values is that a key code value represents a particular
key on the keyboard (the 1 on a keypad is different than the 1 in
the top row, but the key that generates “1” and the key that generates
“!” are the same key) and the character value represents a particular character
(the R and r characters are different).
The mappings between keys and their key codes is dependent on
the device and the operating system. For this reason, you should
not use key mappings to trigger actions. Instead, you should use
the predefined constant values provided by the Keyboard class to
reference the appropriate keyCode properties. For example,
instead of using the key mapping for the Shift key, use the Keyboard.SHIFT constant
(as shown in the preceding code sample).
As with other events, the keyboard event sequence is determined
by the display object hierarchy and not the order in which addEventListener() methods are
assigned in code.
For example, suppose you place a text field called tf inside
a movie clip called container and add an event
listener for a keyboard event to both instances, as the following
container.tf.border = true;
container.tf.type = "input";
trace(event.currentTarget.name + " hears key press: " + String.fromCharCode(event.charCode) + " (key code: " + event.keyCode + " character code: " + event.charCode + ")");
Because there is a listener on both the text field and its parent
container, the reportKeyDown() function is called
twice for every keystroke inside the TextField. Note that for each
key pressed, the text field dispatches an event before the container movie
clip dispatches an event.
The operating system and the web browser will process keyboard
events before Adobe Flash Player or AIR. For example, in Microsoft
Internet Explorer, pressing Ctrl+W closes the browser window before
any contained SWF file dispatches a keyboard event.