Does a form element know its own index number in the forms[].elements[] array?

Dev Shed Forums Sponsor:

August 24th, 2010, 04:06 AM

doctormelodious

Contributing User

Join Date: Aug 2003

Posts: 122

Time spent in forums: 1 Day 9 h 9 m 2 sec
Reputation Power: 64

Does a form element know its own index number in the forms[].elements[] array?

I have a form element that looks like this:

<input type="text" onchange=doSomething(this)>

and a function:

function doSomething(theField){
}

I know that within the function I can access properties of the field (e.g. theField.name and theField.value). But how do I access theField's index number in the form's elements[] array -- from the "this" reference that was passed to the function? I.E. if this field is elements[3], how can I get at that 3?

Thanks!
DM

August 24th, 2010, 08:09 PM

Arty Effem

Contributing User

Join Date: May 2006

Location: England

Posts: 398

Time spent in forums: 1 Week 8 h 25 m 49 sec
Reputation Power: 71

I don't know of such a property but if you need to know it:

Code:

function doSomething(theField)
{
 var elems = theField.form.elements, len = elems.length;

 for( var i = 0; i < len && elems[ i ] !== theField; i++ )
 ;

 /* i holds the element's index */
}

__________________

No it's not 'awesome' - it's just code.

August 27th, 2010, 07:30 PM

doctormelodious

Contributing User

Join Date: Aug 2003

Posts: 122

Time spent in forums: 1 Day 9 h 9 m 2 sec
Reputation Power: 64

Thanks Arty. That's actually pretty close to what I ended up doing.

Quote:

Originally Posted by Arty Effem

I don't know of such a property but if you need to know it:

Code:

function doSomething(theField)
{
 var elems = theField.form.elements, len = elems.length;

 for( var i = 0; i < len && elems[ i ] !== theField; i++ )
 ;

 /* i holds the element's index */
}

Viewing: Dev Shed Forums > Web Design > JavaScript Development > Does a form element know its own index number in the forms[].elements[] array?

« Previous Thread | Next Thread »

Developer Shed Advertisers and Affiliates

Thread Tools	Search this Thread
Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread:

Posting Rules
You may not post new threads You may not post replies You may not post attachments You may not edit your posts vB code is On Smilies are On [IMG] code is On HTML code is Off

View Your Warnings | New Posts | Latest News | Latest Threads | Shoutbox

Forum Jump