title: JavaScript isset() function
body: <p>How to check <code>isset</code> in javascript.</p>
  
  <p>I have used in the following way.</p>
  
  <pre><code>var sessionvalue = document.getElementById('sessionvalue').value;
  
  if(Here I have to check if isset the sessionvalue or not){
  
    if(sessionvalue == "" || sessionvalue == null)
      {
          document.getElementById('sessionvalue').style.borderColor="red";
          return false;
      }
      else
      {
          document.getElementById('sessionvalue').style.borderColor="#ccc";
      }
  }
  </code></pre>