title: How to get 'this' value of caller function?
body: <p>If I have a function like this:</p>
  
  <pre><code>function foo(_this) {
      console.log(_this);
  }
  
  function bar() {}
  bar.prototype.func = function() {
      foo(this);
  }
  
  var test = new bar();
  test.func();
  </code></pre>
  
  <p>then the <code>test</code> instance of <code>bar</code> gets logged.</p>
  
  <p>However, for this to work I have to pass the <code>this</code> in the <code>bar.prototype.func</code> function. I was wondering whether it is possible to obtain the same <code>this</code> value <em>without</em> passing <code>this</code>.</p>
  
  <p>I tried using <code>arguments.callee.caller</code>, but this returns the prototype function itself and not the <code>this</code> value inside the prototype function.</p>
  
  <p>Is it possible to log the <code>test</code> instance of <code>bar</code> by only calling <code>foo()</code> in the prototype function?</p>