title: How to declare a variable inside nested structure?
body: <p>Let's say I have a nested structure with objects and functions in JavaScript as shown below:</p>
  
  <pre><code>this.x = {
     f1: function() {
     },
     f2: function() {
     },
     nested: {
        f3: function() {
        },
        f4: function() {
        }
     }
  }
  </code></pre>
  
  <p>Suppose I want to declare a variable that is only known to to functions f3 and f4. Where and how would I declare this variable?</p>