Iframes

iframes are not supported by Netscape 4.

Using location.href in an iframe to change the page in the iframe does not work in Explorer 4 and 5.0 on Windows and Opera 5 and 6.

On this page I give a short overview of accessing iframes from the page they’re on. Not surprisingly, there are some browser considerations.

An iframe is an inline frame, a frame that, while containing a completely separate page with its own URL, is nonetheless placed inside another HTML page. This gives very nice possibilities in web design. The problem is to access the iframe, for instance to load a new page into it. This page explains how to do it.

Frame or object?

The fundamental question is whether the iframe is seen as a frame or as an object.

In general browsers allow both views on 'real' (hard-coded) iframes, but generated iframes cannot be accessed as frames.

NAME attribute

The most important rule is to give any iframe you create a name attribute, even if you also use an id.

<iframe src="iframe_page1.html"
	id="testiframe"
	name="testiframe"></iframe>

Most browsers need the name attribute to make the iframe part of the frame hierarchy. Some browsers (notably Mozilla) need the id to make the iframe accessible as an object. By assigning both attributes to the iframe you keep your options open. But name is far more important than id.

Access

Either you access the iframe as an object and change its src or you access the iframe as a frame and change its location.href.

document.getElementById('iframe_id').src = 'newpage.html';
frames['iframe_name'].location.href = 'newpage.html';

The frame syntax is slightly preferable because Opera 6 supports it but not the object syntax.

Accessing the iframe

So for a complete cross–browser experience you should give the iframe a name and use the

frames['testiframe'].location.href

syntax. As far as I know this always works.

Accessing the document

Accessing the document inside the iframe is quite simple, provided you use the name attribute. To count the number of links in the document in the iframe, do
frames['testiframe'].document.links.length.

Generated iframes

When you generate an iframe through the W3C DOM the iframe is not immediately entered into the frames array, though, and the frames['testiframe'].location.href syntax will not work right away. The browser needs a little time before the iframe turns up in the array, time during which no script may run.

The document.getElementById('testiframe').src syntax works fine in all circumstances.

The target attribute of a link doesn't work either with generated iframes, except in Opera, even though I gave my generated iframe both a name and an id.

The lack of target support means that you must use JavaScript to change the content of a generated iframe, but since you need JavaScript anyway to generate it in the first place, I don't see this as much of a problem.

Example

<iframe src="iframe_page1.html"
	id="testiframe2"></iframe>

Text size in iframes

A curious Explorer 6 only bug:

When you change the text size through the View menu, text sizes in iframes are correctly changed. However, this browser does not change the line breaks in the original text, so that part of the text may become invisible, or line breaks may occur while the line could still hold another word.