textarea data entry check with alert if empty

I have a form that has a textarea field for input. I want an alert to pop up if the field is empty on submit.

I copied some code that works fine on an input field; however, it does not work for the textarea (it submits with no alerts whether empty or not).
I read through some other questions posted here and made some modifications.
Now, it alerts when empty, but it also alerts when there is text and does not submit.
I am new to this. I am using asp classic.

Code:

<form method="post" action="reasonProcess.asp" name="formName"  onSubmit="return Validate()">
<table >
<tr>
<td>Please enter a reason for the change:<br>
<textarea style="width:675px;height:75px" rows="12" cols="10" name="changereason" > <%=dbchangereason%> </textarea></td>
</tr>
</table><br>    
<input type=button value="Approve" onClick="javascript:saveAndSubmit()" class="btn" style="float:none;font-size:.78em;">
</form>

<script>
function saveAndSubmit()
{
     // Check for reason entered.
  if (!document.formName.changereason.value == '')
  {
    alert("Enter a reason.");
    return false;
  }
    var queryString = "reasonProcess.asp?Approve=Yes";
    document.formName.action=queryString;
    document.formName.submit();
    // window.close();

 }
</script>

This is line of code that works properly with the input text field:

  if (!document.formName.changereason.value)

I have also tried:

 if (!document.formName.changereason.value.length == 0)

and get the alert without text and with text.

Thanks for any help.

Solution

UPDATED

'!' is the logical not operator in JavaScript.

The condition in your code say if the value of changereason textarea is not empty show alert() because of the ! sign that mean not, but what you want is the contrary (if field is empty then show alert), so try just to remove the sign and it will work, do the follow change :

Replace :

if (!document.formName.changereason.value == '')
{
     alert("Enter a reason.");
     return false;
}

By :

if (document.formName.changereason.value == '') //removing the ! sign in this line
{
     alert("Enter a reason.");
     return false;
}

See Working fiddle.

If that not work take a look at External simple page with the same code that is not a fiddle and it should work also in your machine, code of external example :

<!DOCTYPE html>
<html>
    <head><title></title>head>
    <body>
        <form method="post" action="reasonProcess.asp" name="formName"  onSubmit="return Validate()">
            <table >
                <tr>
                    <td>Please enter a reason for the change:<br>
                        <textarea style="width:675px;height:75px" rows="12" cols="10" name="changereason" > <%=dbchangereason%> </textarea>
                    </td>
                </tr>
            </table>
            <br>    
            <input type=button value="Approve" onClick="javascript:saveAndSubmit()" class="btn" style="float:none;font-size:.78em;">
        </form>

        <script>
            function saveAndSubmit()
            {
                 // Check for reason entered.
                if (document.formName.changereason.value == '')
                {
                     alert("Enter a reason.");
                     return false;
                }

                var queryString = "reasonProcess.asp?Approve=Yes";
                document.formName.action=queryString;
                document.formName.submit();
                // window.close();

             }
        </script>
    </body>
</html>

If that work and not the first example then maybe you have another part of code tha caused a problem and that is not referenced in the question.

Good luck.