title: How do I check for null values in JavaScript?
body: <p>How can I check for null values in JavaScript? I wrote the code below but it didn't work.</p>
  
  <pre><code>if (pass == null || cpass == null || email == null || cemail == null || user == null) {      
  
      alert("fill all columns");
      return false;  
  
  }   
  </code></pre>
  
  <p>And how can I find errors in my JavaScript programs?</p>