Question

I’m working with classic ASP.

I have an 2 includes that have 2 different forms on them. They are both unique in name. However, when I try to read the value of the one the elements in the 2nd form I get an error saying it is null. However, when I view the source in Firebug I can see that in face there is a value in that element.

My javascript code:

console.log(document.getElementById('focusValue').value);

Output from firebug:

<input id="focusValue" type="hidden" value="1006" name="focusValue">

Is there something I need to do because there are 2 forms on this “rendered” screen? The only other thing I think I should mention is that these pages are in an iFrame. Not sure if that really matters…

Answer 1

An iFrame creates a separate document within the containing document, you need to get a reference to that document before you can access its content. There is a reasonable tutorial at http://www.dyn-web.com/tutorials/iframes/.

If you only have one iFrame in the page, then you can reference it by:

var frame = window.frames[0];

Or you could use an id with getElementById. To get a reference to the document:

var doc;
if (frame) {
  doc = frame.contentDocument || frame.contentWindow.document;
}

Now you can get to the input element:

var input = doc && doc.getElementById('focusValue');

Of course this all depends on you complying with the same origin policy, otherwise you can’t access the frame content.