FAQ Topic - Why are my Rollovers so slow?

[FAQ server]

-----------------------------------------------------------------------
FAQ Topic - Why are my Rollovers so slow?
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Images are cached by the browser depending on the headers sent by
the server. If the server does not send sufficient information
for the browser to decide the image is cacheable, the browser
will check if the image has been updated everytime you change the
src of an image (in some user settings). To overcome this you
must send suitable headers.

http://www.mnot.net/cache_docs/
===
Postings such as this are automatically sent once a day. Their
goal is to answer repeated questions, and to offer the content to
the community for continuous evaluation/improvement. The complete
comp.lang.javascript FAQ is at http://www.jibbering.com/faq/.
The FAQ workers are a group of volunteers.

[Peter Michaux]

FAQ server wrote:

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FAQ Topic - Why are my Rollovers so slow?
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Images are cached by the browser depending on the headers sent by
the server. If the server does not send sufficient information
for the browser to decide the image is cacheable, the browser
will check if the image has been updated everytime you change the
src of an image (in some user settings). To overcome this you
must send suitable headers.

http://www.mnot.net/cache_docs/

If the rollovers are slow on the first time they are used then
pre-caching the necessary images could help.

[Richard Cornford]

Peter Michaux wrote:

FAQ server wrote:

>-----------------------------------------------------
FAQ Topic - Why are my Rollovers so slow?
-----------------------------------------------------

Images are cached by the browser depending on the headers
sent by the server. If the server does not send sufficient
information for the browser to decide the image is cacheable,
the browser will check if the image has been updated
everytime you change the src of an image (in some user
settings). To overcome this you must send suitable headers.

http://www.mnot.net/cache_docs/

If the rollovers are slow on the first time they are used then
pre-caching the necessary images could help.

If the images are already cached by the browsers then scripted
pre-loading (if it does anything at all) will only make a difference when
the site is first visited, or when re-visited after the browser's cache
has been emptied. Considered and planned configuration of the HTTP
headers sent with resources (particularly as they relate to caching) is
the most significant contributor to an efficient and effective web site.
In comparison scripted approaches pail into barely significant 'hacks'.

Richard.

[RobG]

FAQ server wrote:

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FAQ Topic - Why are my Rollovers so slow?
-----------------------------------------------------------------------

Images are cached by the browser depending on the headers sent by
the server. If the server does not send sufficient information
for the browser to decide the image is cacheable, the browser
will check if the image has been updated everytime you change the
src of an image (in some user settings). To overcome this you
must send suitable headers.

http://www.mnot.net/cache_docs/

It might also be worth mentioning that roll-overs based on sliding
images don't need to modify the src attribute at all. They can also be
implemented using pure CSS, and thereby become independent of script
support.
--
Rob