function checkZip() {
    var coform = document.form2;
   if(coform.zip.value.length<=0){
      alert("Please enter a first name.");
      coform.zip.focus();
      return;
   }
}


<input type="image" onClick="javascript:checkZip();" src="submitbutton.jpg" width="84" height="28" name="image" align="top" border="0">

Hi i have this javascript code. When it pops up the messagebox, it doesnt stay on the page, but it jumps to the next page when i click the submit button. How do i make it so when the messagebox pop up, it makes the user correct the problem, before the pages submits =)

Hi

try this


 function checkdata()
  {
    var blnZipOK = checkZip();
    return blnZipOK;
  }

 function checkZip() {
    var coform = document.form2;
   if(coform.zip.value.length<=0){
      alert("Please enter a first name.");
      coform.zip.focus();
      return false;
   }
   return true;
}

<form name="form1" method="post" action="myNewPage.asp" onsubmit="return checkdata();">
<input type="image" src="submitbutton.jpg" width="84" height="28" name="image" align="top" border="0">

You need to stop the form being posted if the check fails, so call the check zip from within the checkdata() function and return false if there was a problem.
where is the object named in the checkZip function?
any way the syntax would be similar in either case.