title: ReferenceError: str is not defined
body: <p>Im very new to javascript Im working through the <a href="http://www.w3schools.com/js/tryit.asp?filename=tryjs_string_replace" rel="nofollow">w3school tutorial</a>, trying to replace all occurrences within a certain string.</p>
  
  <p>I have the following string <code>08/18/16</code> I would like to replace all occurences of <code>/</code> to <code>,</code></p>
  
  <p>As per W3schools example I try to achieve the above as follow:</p>
  
  <p><code>date1 = str.replace("/",",");</code></p>
  
  <p>However the above results in an error </p>
  
  <blockquote>
    <p>ReferenceError: str is not defined date1 = str.replace("/",",")</p>
  </blockquote>
  
  <p>I would really appreciate it if someone could give the following code a scan. </p>
  
  <pre><code>var firstDate = document.getElementById("firstDate").value;
  var secondDate = document.getElementById("secondDate").value;
  var date1 = firstDate.substring(0,11);
  var date2 = secondDate.substring(0,11);
  date1 = str.replace("/",",");
  date2 = str.replace("/",",");
  </code></pre>