title: how to validate cell number
body: <p>i have to validate the cell no and my requirements are :</p>
  
  <p>1.filed must not empty
  2. if user enter alphabetic value it pop-up "alphabets are not allowed"
  3. field must start with "+" sign
  4. if filed value is less than 13 it pop-up "please enter valid phone no"</p>
  
  <p>i am using this code..</p>
  
  <pre><code>function validateForm()
  {
  
      var cell = document.reg_form.cellno.value;
              if(cell.length==0) 
              {
                  alert("Please enter cell number");
                  reg_form.cellno.focus();
                  return false;
              }
  
             if(isNaN(cell)||cell.indexOf(" ")!=-1)
                {
                   alert("Enter numeric value")
                   return false; 
                }
  
  
              if (cell.charAt(0)!="+")
                {
                  alert("Cell no should start with +");
                  return false
                }
  
                  if(cell.length &lt; 13) 
                 {
                alert("You have entered wrong number");
                reg_form.cellno.focus();
                return false;
          }
  return true;
  }
  </code></pre>
  
  <p>some code is not working here
  when i enter numeric value.. it shows {"Cell no should start with "+"}
  when i put {+} sign it says please enter numeric value
  when i enter only single numeric value like {9} it goes forward.. although in this way field has only 2 value "+" and "9".. it should pop-up {"You have entered wrong number"} </p>
  
  <p>please tell me where i made the mistake....   </p>