title: What's is "this" refer to in Phaser 3?
body: <p>I'm new to Javascript and want to make simple games with Phaser 3, and I found that Javascript seems to be a little different from other OOP languages like C++ or Java. I checked out the tutorial in the official website and some other tutorial page, most of the code is like:</p>
  
  <pre><code>var config = {
      ...
      scene: {
          preload: preload,
          create: create,
          update: update
      }
  }
  var game = new Phaser.Game(config)
  
  function preload(){
      this.load.img(...)
  }
  </code></pre>
  
  <p>My question is what is the ‍<code>"this"</code> in the <code>preload()</code> indicate to? Is it means the <code>"game"</code> we defined before?</p>
  
  <p>And how to check the object's class in console? <code>typeof()</code> only tells <code>"object"</code>.</p>