This is my code for lesson number 7 in the player "Making your first Phaser 3 game" on phaser.io. I created this in case a student needs it for reference.

phaser-07-keyboard-controls.js

const ZERO = 0;
const GAME_WIDTH = 800;
const GAME_HEIGHT = 600;


var config = {
  type: Phaser.AUTO,
  width: GAME_WIDTH,
  height: GAME_HEIGHT,
  physics: {
    default: 'arcade',
    arcade: {
        gravity: { y: 300 },
        debug: false
    }
  },
  scene: {
      preload: preload,
      create: create,
      update: update
  }
};

var game = new Phaser.Game(config);

function preload() {
  this.load.image('sky', 'assets/sky.png');
  this.load.image('ground', 'assets/platform.png');
  this.load.image('star', 'assets/star.png');
  this.load.image('bomb', 'assets/bomb.png');
  this.load.spritesheet(
    'dude',
    'assets/dude.png',
    {
      frameWidth: 32,
      frameHeight: 48
    }
  );
}

function create() {
  this.add.image(GAME_WIDTH/2, GAME_HEIGHT/2, 'sky');

  platforms = this.physics.add.staticGroup();

  platforms.create(400, 568, 'ground').setScale(2).refreshBody();

  platforms.create(600, 400, 'ground');
  platforms.create(50, 250, 'ground');
  platforms.create(750, 220, 'ground');

  player = this.physics.add.sprite(100, 450, 'dude');

  player.setBounce(0.2);
  player.setCollideWorldBounds(true);

  this.anims.create({
    key: 'left',
    frames: this.anims.generateFrameNumbers(
      'dude',
      {
        start: 0,
        end: 3
      }
    ),
    frameRate: 10,
    repeat: -1
  });

  this.anims.create({
    key: 'turn',
    frames: [{
      key: 'dude',
      frame: 4
    }],
    frameRate: 20
  });

  this.anims.create({
    key: 'right',
    frames: this.anims.generateFrameNumbers(
      'dude',
      {
        start: 5,
        end: 8
      }
    ),
    frameRate: 10,
    repeat: -1
  });

  this.physics.add.collider(player, platforms);

  cursors = this.input.keyboard.createCursorKeys();
}

function update() {
  if (cursors.left.isDown)
  {
    player.setVelocityX(-160);
    player.anims.play('left', true);
  }
  else if (cursors.right.isDown) {
    player.setVelocityX(160);
    player.anims.play('right', true);
  }
  else {
    player.setVelocityX(0);
    player.anims.play('turn');
  }

  if(cursors.up.isDown && player.body.touching.down) {
    player.setVelocityY(-330);
  }
}