title: Javascript check if parameter contain this keyword
body: <p>i have a problem for checking javascript function containing <strong>this</strong> keyword or not.</p>
  
  <p>so, this is my code :</p>
  
  <pre><code>function check(el) {        
      if (el === this) {
  
          return el;
      }
      else {
          alert("not contain this keyword");
      }
  }
  check(this);
  </code></pre>
  
  <p>it's always showing <code>alert()</code></p>
  
  <p>i try <code>el</code> <strong>==</strong> <code>this</code>,
  i try <code>el</code> <strong>=</strong> <code>this</code></p>
  
  <p>both are still not working.</p>
  
  <p>is it possible to use <strong>typeof</strong> checking?</p>
  
  <p>what's wrong with my code?</p>