Form field validation

[furtivevole]

In an HTML form, there is a potential field whose existance depends on a previous user action. Before submitting the form, I have to check that the field both exists and is suitably populated. The client-side code for this is:

//Code A
var strNameX=document.FrontPage_Form1.Name;
if(eval(strNameX+"==null")) {
alert ("Wrong (Code A)");
return false;
}

//Code B
var strNameVal=document.FrontPage_Form1.Name.value;
if (strNameVal.length==0) {
alert ("Wrong (Code B)");
return false;
}
else {
alert ("Successful");
return true;
}

If the field does not exist, then code A executes correctly and the function returns false. However if the field does exist - whether or not populated - Code B executes only if code A is commented out.

I guess I've missed something subtle here - can anyone advise please?

 

[LFI]

Try this modification:

//Code A
var strNameX=document.FrontPage_Form1.Name;
//if(eval(strNameX+"==null")) {
if([b]!strNameX[/b]) { [b]//this is how we check for whether a field exists[/b]
 alert ("Wrong (Code A)");
 return false;
}
[b]else
{[/b]        
 //Code B
 var strNameVal=document.FrontPage_Form1.Name.value;
 if (strNameVal.length==0) {
  alert ("Wrong (Code B)");
  return false;
 }
 else {
  alert ("Successful");
  return true;
 }
[b]}//end else[/b]

'hope that helps.

--Dave

 

[furtivevole]

Yes, that worked a treat. I'd not used the else, since when the Code A condition is fulfilled, the function presumably cut out anyway. Thanks.