The buttons property of the Gamepad interface returns an array of GamepadButton objects representing the buttons present on the device.
Each entry in the array is 0 if the button is not pressed, and non-zero (typically 1.0) if the button is pressed.
An array of GamepadButton objects.
Depending on the type of button, we need to access the GamepadButton.value or GamepadButton.pressed properties. This example supports both:
function gameLoop() {
const gp = navigator.getGamepads()[0];
if (gp.buttons[0].value > 0 || gp.buttons[0].pressed) {
b--;
} else if (gp.buttons[1].value > 0 || gp.buttons[1].pressed) {
a++;
} else if (gp.buttons[2].value > 0 || gp.buttons[2].pressed) {
b++;
} else if (gp.buttons[3].value > 0 || gp.buttons[3].pressed) {
a--;
}
ball.style.left = `${a * 2}px`; // ball is a UI widget
ball.style.top = `${b * 2}px`;
requestAnimationFrame(gameLoop);
}