keyPressed

KeyPressed is a name used in several programming environments to handle keyboard input events. In the related editors and libraries, it is commonly implemented as an event handler function that executes when a user presses a key. Some environments also expose a boolean variable named keyPressed that indicates when any key is currently pressed. The term is thus both a function and, in some contexts, a state indicator.

In Processing, keyPressed is an event-handling function you can define to run code in response to a key press. When a key is pressed, the function is invoked, and two built‑in variables provide details: key holds the character value of the key, and keyCode holds a code for special keys. If a coded key (such as an arrow key) is pressed, key will equal CODED, and keyCode will contain the specific value (e.g., LEFT, RIGHT, UP, DOWN). The boolean keyPressed becomes true while a key is down, and keyReleased() is called when the key is released.

In p5.js, keyPressed is a callback that fires when a key is pressed in the browser. Inside the function, key contains the last key pressed as a string, and keyCode contains the numeric code. P5.js also provides constants such as LEFT_ARROW, UP_ARROW, and functions like keyIsDown(code) to test the state of a key over time.

Common usage patterns include distinguishing between ordinary and coded keys, handling repeated presses, and implementing keyboard controls for interactive programs. While the exact behavior can vary by language and environment, keyPressed generally serves as a simple, event-driven mechanism to respond to user input from the keyboard. See also KeyEvent, KeyListener, and related input handling concepts in the respective platform documentation.