title: Pass by Value and Pass by Reference in Javascript
body: <p>Now that I've been working on Angular2 for almost 3 months, I've encountered a few scenarios which led me to wonder how does this happen ?</p>
  
  <p>In the case of special <code>this</code> keyword it's obvious that it's passing a reference or instance of the related <code>DOM Object</code> or <code>Class</code> for Example.</p>
  
  <p>But then there is another thing called <code>ControlGroup</code> which also does the same whenever it's assigned to another variable. And both the variables have access to same instance of that <code>ControlGroup</code>.</p>