phaser/examples/input/keyboard.js

var game = new Phaser.Game(800, 600, Phaser.CANVAS, 'phaser-example', { preload: preload, create: create, update: update, render: render });

var ufo;
var leftBtn;
var rightBtn;
var speed = 4;

function preload() {

    game.world.setBounds(0,0,1280, 600);

    game.load.image('ground', 'assets/tests/ground-2x.png');
    game.load.image('river', 'assets/tests/river-2x.png');
    game.load.image('sky', 'assets/tests/sky-2x.png');
    game.load.image('cloud0', 'assets/tests/cloud-big-2x.png');
    game.load.image('cloud1', 'assets/tests/cloud-narrow-2x.png');
    game.load.image('cloud2', 'assets/tests/cloud-small-2x.png');

    game.load.spritesheet('button', 'assets/buttons/arrow-button.png', 112, 95);

    game.load.image('ufo', 'assets/sprites/ufo.png');
    
}

function create() {

    // background images
    game.add.tileSprite(0, 0,1280,600, 'sky');
    game.add.sprite(0, 360, 'ground');
    game.add.sprite(0, 400, 'river');
    game.add.sprite(200, 120, 'cloud0');
    game.add.sprite(-60, 120, 'cloud1');
    game.add.sprite(900, 170, 'cloud2');

    // Create a ufo sprite as player.
    ufo = game.add.sprite(320, 240, 'ufo');
    ufo.anchor.setTo(0.5, 0.5);

    // Make the default camera follow the ufo.
    game.camera.follow(ufo);

    // Add 2 sprite to display hold direction.
    leftBtn = game.add.sprite(160 - 112, 200, 'button', 0);
    leftBtn.alpha = 0;
    rightBtn = game.add.sprite(640 - 112, 200, 'button', 1);
    rightBtn.alpha = 0;

}

function update() {

    // Check key states every frame.
    // Move ONLY one of the left and right key is hold.

    if (game.input.keyboard.isDown(Phaser.Keyboard.LEFT))
    {
        ufo.x -= speed;
        ufo.angle = -15;
        leftBtn.alpha = 0.6;
    }
    else if (game.input.keyboard.isDown(Phaser.Keyboard.RIGHT))
    {
        ufo.x += speed;
        ufo.angle = 15;
        rightBtn.alpha = 0.6;
    }
    else
    {
        ufo.rotation = 0;
        leftBtn.alpha = rightBtn.alpha = 0;
    }

}

function render() {

    game.debug.renderText('Hold left/right to move the ufo.');

}