Form validation for file extension upload

[techskool]

Im a total incompetent when it comes to JavaScript as i work soley in ASP and SQL, but against my better judgement tried some client side form validation the other day.

I wrote and hacked this together but it falls over.

Can you tell me whats up with it?

Thanks

Dave

function onSubmitForm() {
if (document.frmSend.attach.value == "")
alert("Please press the browse button and pick a file.")
else if (document.frmSend.attach.value != "")

{
var ext = document.frmSend.attach.value;
var VARext = new Array("doc","xls","ppt","PDF");
ext = ext.substring(ext.length-3,ext.length);
ext = ext.toLowerCase();
for (i = 0;i < VARext.length;i++)
{
if (ext == VARext)
return true;
else
alert('You selected a .'+ext+' file; please select a valid file instead!');
return false;
}
}

}

 

[BillyRayPreachersSon]

Hard to "fix" when you haven't said what's wrong. I haven't tested it, but try this instead:

function onSubmitForm() {
	var formObj = document.forms['frmSend'];
	var ext = formObj.attach.value;
	if (ext == '')
		alert('Please press the browse button and pick a file.');
	else {
		var VARext = ['doc', 'xls', 'ppt', 'PDF'];
		ext = ext.substring(ext.length-3, ext.length).toLowerCase();
		for (var i=0; i<VARext.length; i++) {
			if (ext == VARext[i])
				return (true);
			else {
				alert('You selected a .' + ext + ' file; please select a valid file instead!');
				return (false);
			}
		}
	}
}

I added a missing set of braces around the last if/else set, and restructured some of the code. Also, the most common error is using "document.fornName", which works in IE, but not much else (and isn't DOM "compliant", anyway).

Hope this helps,
Dan

 

[simonchristieis]

this logic seems wrong:

for (i = 0;i < VARext.length;i++)
{
 if (ext == VARext[i])
  return true;
 else
  alert('You selected a .'+ext+' file; please select a valid file instead!');
 return false;
}

try something like

var x = false
for (i = 0;i < VARext.length;i++)
{
 if (ext == VARext[i])
  x = true;
}

if(!x)
 alert('You selected a .'+ext+' file; please select a valid file instead!');

return x;

hth

simon

 

[techskool]

That ideal

any thanks for all the help guys.

Dave

 

[techskool]

sorry that should read many thanks!