Input: keyboard, pointer and gamepad

Keyboard goes through named actions

Do not poll key codes. Bind a key to an action string, then poll the action, this is what lets gamepad and virtual controls map onto the same handling.

import { input } from "melonjs";

input.bindKey(input.KEY.LEFT,  "left");
input.bindKey(input.KEY.RIGHT, "right");
input.bindKey(input.KEY.X,     "jump", true);   // true = locked: one press per keydown

// in update()
if (input.isKeyPressed("left"))  { /* … */ }
if (input.isKeyPressed("jump"))  { /* fires once per press, not per frame */ }

The third argument to bindKey is lock (default false). Without it, isKeyPressed stays true for as long as the key is held, correct for movement, wrong for jump or fire. A locked action stays consumed until the key is released or you call input.unlockKey("jump"). Use input.keyStatus(action) when you want the raw held/not-held state regardless of locking.

A poll can miss a press entirely

isKeyPressed is sampled once per frame, and keyup decrements the key's counter the moment it arrives, locked or not. A press that goes down and up between two frames therefore leaves the counter back at zero and is never seen. At 60fps that is anything under ~16ms: rare from a human finger, routine from a synthetic event, and more likely the slower the frame rate.

For a screen where a missed press is a dead end, a splash, a "press any key", a notice to acknowledge, listen for the event instead, which cannot be missed:

import { event } from "melonjs";

// action is the bound action name, or undefined for an unbound key
const onKey = (action) => { if (action === "menuSelect") continue(); };
event.on(event.KEYDOWN, onKey);      // in onResetEvent
event.off(event.KEYDOWN, onKey);     // in onDestroyEvent, it does not self-remove