Targeting Frames

One of the challenges of managing a framed document is coordinating where linked documents display. By default, a linked document loads into the same window as the link; however, it is often desirable to have a link in one frame load a page into a different frame in the frameset. For instance, this is the desired effect for a list of navigation links in a narrow frame that loads content into a larger main frame on the page.

To load a new linked page into a particular frame, you first need to assign a name to the targeted frame using the name attribute in the <frame> tag, as follows:

<FRAME src="original.html" NAME="main">

Now you can specify that frame by name within any anchor (<a>) tag with the target attribute, as shown in this example:

<A href="new.html" TARGET="main">...</A>

The document new.html will load into the frame named "main".

If a link contains a target name that does not exist in the frameset, a new browser window is opened to display the document, and that window is given the target's name. Subsequent links targeted to the same name will load in that window.

The <base> tag

If you know that you want all the links in a given document to load in the same frame (such as from a table of contents into a main display frame), you can set the target once using the <base> tag instead of setting the target within every link in the document (saving a lot of typing and extra characters in the HTML document).

Placing the <base> tag in the <head> of the document, with the target frame specified by name, causes all the links in the document to load into that frame. The following is a sample targeted base tag:

<HEAD>
<BASE TARGET="main">
</HEAD>

Targets in individual links override the target set in the <base> tag at the document level.

Reserved target names

There are four standard target names for special redirection actions. Note that all of them begin with the underscore ( _ ) character. You should avoid naming your frames with a name beginning with an underscore as it will be ignored by the browser. The four reserved target names are:

_blank
<>A link with target="_blank" opens a new, unnamed browser window to display the linked document. Each time a link that targets _blank is opened, it launches a new window, potentially leaving the user with a mess of open windows. This can be used with any link, not just those in a frames context.

_self
This is the default target for all <a> tags; it loads the linked document into the same frame or window as the source document. Because it is the default, it is not necessary to use it with individual <a> tags, but it may be useful within the <base> tag of the document.

_parent
A linked document with target="_parent" loads into the parent frame (one step up in the frame hierarchy). If the link is already at the top-level frame or window, it is equivalent to _self. Figure 14-7 demonstrates the effects of a link targeting the parent frame.
The _parent target name works only when the nested framesets are in separate documents. It does not work for multiple nested framesets within a single frameset document (such as the example shown under "Nesting Frames" earlier in this chapter).

Figure 14-7. In nested framesets, the _parent target links to the parent frameset

_top
This causes the document to load at the top-level window containing the link, replacing any frames currently displayed. A linked document with target= "_top" "busts out" of its frameset and is displayed directly in the browser window, as shown in Figure 14-8.