Check to see if a form element exists

Slippenos · Sep 10, 2005

I have a form that may or may not contain certain form elements depending on server-side ASP conditions.

With that being said, how can I test to see if a form element is present.

I tried:

Code:

if ( document.getElementById( anElement ) != "undefined") 

   {

   my validation code

   }

AND

Code:

if ( document.getElementById( anElement ) != null )

   {

   my validation code

   }

To no avail.

Any thoughts?

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Lrnmore · Sep 10, 2005

Do your form fields have their own id's?
Are they unique?

You are pretty close with the above attempt:

Code:

<script type="text/javascript">
var arr = ['t1','t2'];

function ckFields(){
for(var j = 0; j < arr.length; j++){
    if(document.getElementById(arr[j]) != undefined)
    alert(document.getElementById(arr[j]).name);
  }
}
</script>
</head>
<body onload="ckFields()">
<form name="f1">
<input type="text" id="t1" name="t1" />
</form>

Thanks,
--Mark

Slippenos · Sep 10, 2005

Hmm...

I wanted to accomplish something similar to:

Code:

if( cssign.getElementByName( EstimateStatus ) != undefined)

	{


	if( cssign.EstimateStatus.value == "Nothing" )
	
		{
		
		alert( "You have not changed the status of the Estimate" );
		cssign.EstimateStatus.focus( );
		return( false );
		
		}

.. Whith an onsubmit event. Is this possible?

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Slippenos · Sep 10, 2005

I forgot the '}' at the end.

I forgot to mention I am generating a 'EstimateStatus' is undefined error message.

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Lrnmore · Sep 10, 2005

Is there any reason you can't use the element name like so:

Code:

<script type="text/javascript">

function ckForm(form){
if(form.elements['EstimateStatus'] && 
   form.elements['EstimateStatus'].value == 'Nothing'){
   alert('Your Note');
   return false;
   }
if(form.elements['EstimateStatusB'] && 
   form.elements['EstimateStatusB'].value == 'Nothing'){
   alert('Your Note');
   return false;
   }
return true;      
}
</script>
</head>
<body>
<form name="f1" onSubmit="return ckForm(this)">
<input type="text" id="t1" name="t1" /><br />
<select name="EstimateStatus">
  <option selected value="Nothing" />Nothing
  <option value="Something" />Something  
</select>
<input type="submit">
</form>

What type of form fields are you working with?

Thanks,
--Mark

Slippenos · Sep 12, 2005

The problem was that the form fields didn't always exist. For instance ...

Code:

<script language = "javascript">
<!--

function test( )

{

if( document.form.thefield.value.length > 1 )

   {

   alert("The field 'thefield' exists!");

   }

}

//-->
</script>

Code:

<form name = "form" onsubmit = "return test( );">

Code:

<% If Len( objRS("thisfield") ) > 0 Then %>

<input type = "text" name = "thatfield">

<% Else %>

<input type = "text" name = "thefield">

<% End If %>

It was poor programming on my part, but that was the gist
of what I was doing.

However, I did resolve my issue. I said something to the tune of:

Code:

<% If Len( objRS("thisfield") ) > 0 Then %>

<input type = "text" name = "thatfield">

<% Else %>

<input type = "hidden" name = "thatfield" value = "<%=objRS("thatfield")%>">

<% End If %>

Thanks for the posts.

-Mike

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Lrnmore · Sep 12, 2005

Hi Slippenos,

If you notice there is no form field 'EstimateStatusB' in the above example.
That is what the first part of our 'if' does.
(Makes sure there is a form field with that name before testing the value.)

Code:

if(form.elements['EstimateStatusB'] &&
   form.elements['EstimateStatusB'].value == 'Nothing'){
   alert('Your Note');
   return false;
   }

Thanks,
--Mark

adam0101 · Sep 12, 2005

For a function that checks the existence of an object, see my post on thread216-1106645.

Adam

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Check to see if a form element exists

Slippenos

MIS

Lrnmore

Technical User

Slippenos

MIS

Slippenos

MIS

Lrnmore

Technical User

Slippenos

MIS

Lrnmore

Technical User

adam0101

Programmer

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