title: Form validation of numeric characters in JavaScript
body: <p>I would like to perform form validation using JavaScript to check for input field only to contain numeric characters.So far, the validation checks for the field not being empty - which works fine.However, numeric characters validation is not working.I would be grateful for any help.Many thanks.</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
  //form validation
  function validateForm()
  {
  var x=document.forms["cdp_form"]["univer_number"].value
  if (x==null || x=="")
    {
    alert("University number (URN) field must be filled in");
    cdp_form.univer_number.focus();
    return false;
    }
  else if (is_valid = /^[0-9]+$/.test(x))
      {
      alert("University number (URN) field must have numeric characters");
      cdp_form.univer_number.focus();
      return false;
    }
  }
  &lt;/script&gt;
  
  
  &lt;input type ="text" id="univer_number" maxlength="7"    size="25"   name="univer_number" /&gt;
  </code></pre>