Javascript Form Validation Problem

i'm trying to put together some Javascript form validation to check that all fields have been completed before submitting.

So far i have this in my tag, and the function for the first form field only:

<script type="text/javascript">

function validate(form) {
fail = vaildatecompany_name(preview.company_name.value)

if (fail =="" return true

else { alert(fail); return false }
}

function validatecompany_name(field) {
    if (field == "" return "No Company Name was entered. \n"
return ""
}
</script>

And the first field i'm trying to validate is:

<form action="jobpreview.php" name = "preview" method="post" form enctype="multipart/form-data" onSubmit = "return validate(this)">

<ul>
<li><label for = "company_name">Company Name</label>    
<input type="text" name="company_name"/>
</li>

Can someone explain what i'm doing wrong? It's not bringing up any alert when i submit the form with no entry in the field and is just going through as normal.

Thanks Dan

Your code is riddled with errors. You spelled your call to the validatecompany_name function wrong, your if statements aren't properly formed (errant opening bracket) and you don't pass the form variable properly (you treat preview and form interchangeably). This works, although it's not great code:

function validate(form){
  var fail = validatecompany_name(form.company_name.value);
    if (fail==""){
      return true;
    } else {
      alert(fail);
      return false;
    }
  }

function validatecompany_name(field){
  if (field == "") return "No Company Name was entered. \n";
  return "";
}