Input

The Input class manages keyboard and mouse input for a game or application by registering event listeners on a given canvas element. It provides methods to check for held and pressed keys, as well as mouse positions and button presses.

Static Properties

Input.KEYS

Input.KEYS;

A constant object mapping key names to their string representations. This includes common keyboard keys such as alphanumeric keys, special keys, and function keys.

Example:

Input.KEYS.ENTER; // "Enter"
Input.KEYS.ARROW_LEFT; // "ArrowLeft"

Input.MOUSE

Input.MOUSE;

A constant object mapping mouse buttons to their numerical values.

• LEFT (0)
• MIDDLE (1)
• RIGHT (2)

Example:

Input.MOUSE.LEFT; // 0
Input.MOUSE.RIGHT; // 2

Constructor

new Input(canvas)

Initializes the Input object, attaches event listeners for keyboard and mouse events to the provided canvas element.

• Parameters:
  • canvas (HTMLCanvasElement): The canvas element to capture input events from.

Example:

const input = new Input(document.getElementById('gameCanvas'));

Methods

initEventListeners()

Sets up event listeners for keydown, keyup, mousemove, mousedown, and mouseup events. Automatically called in the constructor.

• Returns: void

---

isKeyHeld(key)

Checks if a key is currently being held down.

• Parameters:

  • key (String): The key to check (case-insensitive).

• Returns: Boolean: true if the key is being held down, false otherwise.

Example:

if (input.isKeyHeld(Input.KEYS.ARROW_UP)) {
  // Move player up
}

---

isKeyPressed(key)

Checks if a key was pressed once (and resets the key state to prevent continuous firing).

• Parameters:

  • key (String): The key to check (case-insensitive).

• Returns: Boolean: true if the key was pressed, false otherwise.

Example:

if (input.isKeyPressed(Input.KEYS.ENTER)) {
  // Confirm selection
}

---

getMousePosition()

Returns the current position of the mouse relative to the canvas.

• Returns: Object: An object with x and y properties representing the mouse’s position.

Example:

const mousePos = input.getMousePosition();
console.log(`Mouse X: ${mousePos.x}, Mouse Y: ${mousePos.y}`);

---

isMouseButtonHeld(button)

Checks if a specific mouse button is currently being held down.

• Parameters:

  • button (Number): The mouse button to check (e.g., Input.MOUSE.LEFT).

• Returns: Boolean: true if the button is being held down, false otherwise.

Example:

if (input.isMouseButtonHeld(Input.MOUSE.LEFT)) {
  // Dragging logic
}

---

isMouseButtonPressed(button)

Checks if a specific mouse button was pressed once (and resets the button state).

• Parameters:

  • button (Number): The mouse button to check (e.g., Input.MOUSE.LEFT).

• Returns: Boolean: true if the button was pressed, false otherwise.

Example:

if (input.isMouseButtonPressed(Input.MOUSE.LEFT)) {
  // Select tile
}