What's wrong with image maps?
- They are invisible and unusable to text mode browsers, and to graphic
browsers with graphics disabled (usually to facilitate browsing over slow
lines, such as dial-ins).
- Unlike HTML lists or menus, they are not scalable; an image map 700
pixels wide will not be visible on a screen or window 640 pixels wide
without scrolling.
- Their colors and text fonts are fixed, so they cannot be configured by
sight-impaired users.
- The graphic files are large, often in the range of 15-100k, compared
with a kilobyte or less for a text menu.
- The URL of the destination link does not appear to the user until he or
she selects the link. Nor can the browser tell exactly which areas of the
map are clickable.
- Most importantly, the results of an image-map transaction are unknown to
the browser, so that future accesses to the same map location cannot be
retrieved from the browser cache, nor from a
proxy cache, resulting in much
slower performance.
Some of these warnings do not apply to the
client-side image map, a new kind of image map that is being
implemented on some browsers. In a client-side map, the destination URL is
visible to the browser, hence cacheable. Client-side image maps are part of
the new
<OBJECT> element; they are also implemented, somewhat
differently, in the
<MAP> element, introduced by Spyglass Corporation and
partially supported by Netscape 2.0 and Microsoft Internet Explorer.
Warren Steel
(mudws at olemiss.edu)
Last modified 24 October 1997
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