title: How to do Null value check in Java script?
body: <p>in jsp i am writing java script. Please help me how to do null check in javascript? i have drop down list. onchange some action should happen. pleae find below code. </p>
  
  <pre><code>&lt;select onchange="openPage(this.value)"&gt;
  </code></pre>
  
  <p>here some times this.value can be null. simply i need to do null check.when it is not null then only it should call openPage() method. please help me how to solve?</p>
  
  <p>Thanks!</p>