title: Checking if enter key pressed in the text box
body: <p>I am using following code to check if enter key was pressed in textbox but I am getting 
  type error <strong>TypeError: e is undefined</strong></p>
  
  <pre><code>&lt;html lang="en"&gt;
      &lt;head&gt;
          &lt;meta http-equiv="content-type" content="text/html; charset=utf-8"&gt;
          &lt;title&gt;demo&lt;/title&gt;
          &lt;script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"&gt;&lt;/script&gt;
          &lt;script&gt;
  function memSort(e){        
          if(e.keyCode === 13){
              alert("Enter was pressed ");
          }       
  }
  &lt;/script&gt;
      &lt;/head&gt;
      &lt;body&gt;  
          &lt;div class="searchBox"&gt;
              &lt;div class="keyname"&gt;Keyword : &lt;/div&gt;          
              &lt;input name="usersearch" id="usersearch" type="text" value="" onKeydown="memSort();"/&gt;
              &lt;div id="listOrders"&gt;&lt;/div&gt;
          &lt;/div&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>