Keyboard

Installation

function install_keyboard(enable_keys?: number[]): number;
function remove_keyboard(): number;

Attaches keydown/keyup listeners to document. By default, all keys except F1–F12 and Escape have their browser default action suppressed (no back navigation, no scrolling, etc.).

Pass enable_keys to customise which keys keep their default browser behavior:

// Allow F5 (reload) and Escape, suppress everything else
install_keyboard([KEY_F5, KEY_ESC]);

Returns 0 on success, -1 if already installed.

key array

const key: boolean[];

Indexed by key code. key[KEY_A] is true while the A key is held down.

install_keyboard();

// In your game loop:
if (key[KEY_LEFT]) player.x -= 2;
if (key[KEY_RIGHT]) player.x += 2;
if (key[KEY_SPACE]) shoot();

key_shifts

let key_shifts: number;

Bitmask of currently held modifier keys. Check with the KB_*_FLAG constants:

if (key_shifts & KB_SHIFT_FLAG) console.log("Shift held");
if (key_shifts & KB_CTRL_FLAG) console.log("Ctrl held");
if (key_shifts & KB_ALT_FLAG) console.log("Alt held");

Shift flag constants

Constant	Value
KB_SHIFT_FLAG	0x0001
KB_CTRL_FLAG	0x0002
KB_ALT_FLAG	0x0004
KB_LWIN_FLAG	0x0008
KB_RWIN_FLAG	0x0010
KB_MENU_FLAG	0x0020
KB_COMMAND_FLAG	0x0040
KB_SCROLOCK_FLAG	0x0100
KB_NUMLOCK_FLAG	0x0200
KB_CAPSLOCK_FLAG	0x0400
KB_INALTSEQ_FLAG	0x0800

Key buffer

const key_buffer: number[];

function keypressed(): boolean;
async function readkey(): Promise<number>;
function clear_keybuf(): void;

key_buffer stores key codes as they are pressed. readkey() is an async function that resolves with the next key from the buffer, waiting if it's empty:

const k = await readkey();
if (k >> 8 === KEY_ENTER) startGame();

Key codes

// Letters
KEY_A ... KEY_Z

// Numbers (top row)
KEY_0 ... KEY_9

// Numpad
KEY_0_PAD ... KEY_9_PAD
KEY_PLUS_PAD, KEY_MINUS_PAD, KEY_ASTERISK, KEY_SLASH_PAD
KEY_DEL_PAD, KEY_ENTER_PAD, KEY_EQUALS_PAD

// Function keys
KEY_F1 ... KEY_F12

// Navigation
KEY_ESC, KEY_TAB, KEY_ENTER, KEY_BACKSPACE, KEY_SPACE
KEY_INSERT, KEY_DEL, KEY_HOME, KEY_END, KEY_PGUP, KEY_PGDN
KEY_LEFT, KEY_RIGHT, KEY_UP, KEY_DOWN

// Punctuation
KEY_MINUS, KEY_EQUALS, KEY_TILDE, KEY_BACKQUOTE, KEY_SEMICOLON
KEY_COLON, KEY_QUOTE, KEY_BACKSLASH, KEY_OPENBRACE, KEY_CLOSEBRACE
KEY_COMMA, KEY_STOP, KEY_SLASH

// Modifiers
KEY_LSHIFT, KEY_RSHIFT
KEY_LCONTROL, KEY_RCONTROL
KEY_ALT, KEY_ALTGR
KEY_LWIN, KEY_RWIN
KEY_MENU, KEY_CAPSLOCK, KEY_NUMLOCK, KEY_SCRLOCK
KEY_PRTSCR, KEY_PAUSE

Simulating key presses

function simulate_keypress(key: number): void;
function simulate_ukeypress(key: number, scancode: number): void;

Pushes a key code into key_buffer and sets the corresponding key[] entry.

Other (stubs / no-ops)

function poll_keyboard(): number; // always 0
function keyboard_needs_poll(): boolean; // always false
function scancode_to_ascii(scancode: number): number;
function scancode_to_name(scancode: number): number;
function set_leds(leds: number): void;
function set_keyboard_rate(delay: number, repeat: number): void;