LeCodesdocs

Input

Keyboard polling. Input answers one question — is this key held right now? — and you ask it every frame inside setLoop. There are no key events (no keydown/keyup listeners); for taps and drags on objects use pointer events instead.

At a glance

TypeScript
setLoop(dt => {
  if (Input.key('ArrowRight')) player.x += 200 * dt
  if (Input.key('ArrowLeft'))  player.x -= 200 * dt
})

Polling

TypeScript
Input.key(code: string): boolean    // true while the key is held

code is a KeyboardEvent.code-style string — the physical key, not the typed character: 'ArrowRight', 'KeyW', 'Space', 'Enter', 'ShiftLeft'. WASD is 'KeyW'/'KeyA'/ 'KeyS'/'KeyD' regardless of keyboard layout.

Note

polling, not events — multiply movement by dt (seconds) so speed is frame-rate-independent.

"Pressed this frame" — edge detection

Input.key is level-triggered (true every frame the key is down). For actions that must fire once per press (jump, shoot), keep a wasDown map and latch it at the end of the frame:

TypeScript
const wasDown: Record<string, boolean> = {}
const pressed = (code: string) => Input.key(code) && !wasDown[code]

setLoop(dt => {
  if (pressed('Space')) player.jump()               // fires once per key-down
  if (Input.key('ArrowRight')) player.x += 200 * dt // fires every frame while held

  wasDown['Space'] = Input.key('Space')             // latch at end of frame
})

Latch every key you edge-detect — one line per key at the bottom of the loop.

Pitfalls

TypeScript
// ✗ level-triggered check for a one-shot action — jumps every frame while Space is held
if (Input.key('Space')) player.jump()
// ✓ edge-detect with the wasDown recipe above
if (pressed('Space')) player.jump()

// ✗ character codes — layout-dependent and not what Input.key expects
Input.key('w')
// ✓ physical key codes
Input.key('KeyW')

See also

← BackdeviceNext →Touch events