Checking blank field in text area
===

I have 3 text box and 1 textarea field.
id, name, address, contact.
All are java scripted in the purpose of checking blank field.
I did it in this way :

javascript code :

    function checkForm()	
    {
    var id=document.getElementById("id").value;
    var name=document.getElementById("name").value;
    var address=document.getElementById("address").value;
    var contact=document.getElementById("contact").value;

			
    if(id.length<1 )		
    {
    alert("Please enter all the informations!");
    return false;
    }
    if(name.length<1 )		
    {
    alert("Please enter the name!");
    return false;
    }
    if(address.length<1 )		
    {
    alert("Please enter the address!");
    return false;
    }
    if(contact.length<1 )		
    {
    alert("Please enter the contact!");
    return false;
    }



html code :

    <form method="post" action="clients.php" onSubmit="return checkForm()">
      id <input type="text" name="id" id="id">
      name <input type="text" name="name" id="name">
      address <textarea name="address" id="address"> </textarea>
      contact <input type="text" name="contact" id="contact">
      <input type="submit" name="submit" value="Enter">
    </form>

All are working except textarea. I am trying with some other code, founded in the internet, but those aren't working. Maintaining the serial (id then name then address then contact....) how can i check the blank space of the textarea?

Thanks a lot in advance.