Phaser Physics with Movement

script.js

var game = new Phaser.Game(
  200, //The width in pixels
  200, //The height in pixels
  Phaser.AUTO, //The render system
  "phaser", //The element
  {
    preload: preload, // The preload function
    create: create, // The create function
    update: update // The update function
  }
);

// Create the variable outside of any one function scope
var sprite;

function preload() {}

function create() {

  // Start the Arcade physics system
  game.physics.startSystem(Phaser.Physics.ARCADE);

  sprite = game.add.sprite(
    50, // The x position
    50, // The y position
    'sprite' // The image cache-key
  );

  // Enable Arcade physics on 'sprite'
  game.physics.arcade.enable(sprite);

}

function update() {

  sprite.body.velocity.x = 0;

  if (game.input.keyboard.isDown(Phaser.Keyboard.LEFT)) {
    sprite.body.velocity.x = -40; // Move left
  }
  if (game.input.keyboard.isDown(Phaser.Keyboard.RIGHT)) {
    sprite.body.velocity.x = 40; // Move right
  }
}