Gamepad Test

A gamepad test reads the signals your controller sends to the browser through the W3C Gamepad API and shows them in real time: every button press, analog stick position, trigger depth, D-pad direction and rumble motor. It is the fastest way to check whether a controller works before a game, diagnose a sticky face button, catch stick drift on an aging pad, or verify that both rumble motors fire. The page highlights each input on an on-screen Xbox-style layout, reports raw axis and trigger values, and keeps a short event log. Because the Gamepad API only exposes a controller after you press a button on it, the page will ask you to press any key first - that is a browser security rule, not a fault with your pad. Everything runs locally in your browser; no input data leaves your device.

The browser exposes gamepads through the W3C Gamepad API. A controller is represented by a Gamepad object obtained from navigator.getGamepads(), which returns up to four slots. Each gamepad carries an id string (vendor and product), a mapping field ('standard' for Xbox-layout devices, empty otherwise), a buttons array and an axes array. Under the standard mapping, buttons has 17 entries: four face buttons (A/B/X/Y), two bumpers (LB/RB), two analog triggers (LT/RT), Select/Start, two stick-clicks (L3/R3), four D-pad directions and the Home/Guide button. Each button exposes .pressed (boolean) and .value (0 to 1 - triggers go analog, digital buttons are 0 or 1). The axes array holds four values in the range -1 to 1: left stick X/Y then right stick X/Y. The API is poll-based, not event-based, so the page runs a requestAnimationFrame loop and reads a fresh snapshot every frame. To avoid useless re-renders while the pad is idle, it only updates state when gamepad.timestamp changes - that timestamp advances on every new input report. Connect and disconnect arrive as gamepadconnected and gamepaddisconnected window events. For security, a gamepad object stays null until the user presses a button on it, so the page cannot read a freshly plugged-in pad silently. Rumble is optional: if gamepad.vibrationActuator exists, calling playEffect('dual-rumble', { duration, weakMagnitude, strongMagnitude }) drives the two motors; Safari and some Chromium builds do not implement it, which is why the page feature-detects it and disables the buttons otherwise.

• navigator.getGamepads() returns up to four slots; a pad is only non-null after you press a button on it.
• Standard mapping: buttons[0-3] face, [4-5] bumpers, [6-7] analog triggers, [8-9] Select/Start, [10-11] L3/R3, [12-15] D-pad, [16] Home.
• axes[0-1] is the left stick (X, Y), axes[2-3] the right stick, each ranging -1 to 1.
• Polling model: a requestAnimationFrame loop reads snapshots; gamepad.timestamp gates updates so idle frames do nothing.
• Rumble via gamepad.vibrationActuator.playEffect('dual-rumble', ...) - feature-detected, not supported in every browser.
• gamepadconnected / gamepaddisconnected events signal connect and disconnect; the pad's .index identifies its slot.