For example in the seam doc reference (single html page) http://docs.jboss.com/seam/2.1.0.A1/reference/en/html_single/#d0e336
in the url the #d0e336 marks the section 'Understanding the code' within the whole html page. If you do a view source you could see that section of the page is marked with anchor href to #d0e336
URI combined with this #mark points to the particular section of the page, this helps people to bookmark page, and return exactly there when they come back.
Lets get into some more interesting stuff with the # sign. Whenever you request a page with #mark in the end; the browser sends GET request only with url up to the #mark. The part that comes after the # sign is never sent to server.
If you request for http://mypage.com/page#profile, the browser sends the request as 'http://mypage.com/page' ripping off the # sign and the text after that. Once the browser loads the page, it tries to locate the anchor with matching href '#profile' () and positions the page. If the browser cannot find the specified anchor href it just ignores it and shows the page as it is.
Given that the text after the #mark concerns only for the client and also that browser ignores it for taking any action if the particular anchor is missing in the markup. There are some potential uses for the # sign.
- fancy url
- could be potentially used to maintain client-side state!
- generate unique bookmark-able url
fancy url:
http://mail.google.com/mail/#inbox
http://mail.google.com/mail/#sent
As you see the server url is just http://mail.google.com/mail/, but the browser displaying #inbox denotes that you are in inbox view.
maintain client-state:
Say there are 2 tabs in a page, the user wants to bookmark the page along with the current tab that he is working with. Thereby whenever he loads the page with the saved bookmark; the page should be loaded with the same tab highlighted of the group.
You could add an identifier with the # sign on the url, and use client side javascript to parse the location and pick the identifier to determine which tab should be highlighted.
Some javascript libraries use this as trick to generate part of the page in the browser. The iUI library which generates iphone style webpages actually uses the same trick. It maintains client state by this identifier, and uses javascript to re-render part of the page in iphone style mock up.
http://m.linkedin.com/#_home
unique bookmark-able url:
Say you use greasemonkey to customize a webpage. And you set up that custom script to run for a particular url/site. Now you want to test a new script with the same url, you could add some identifier along the pound sign to create a unique url. Map the script to be triggered for this new unique url, so the same site will be handled by different greasemonkey scripts based on the url you load.
reference:
http://gbiv.com/protocols/uri/rfc/rfc3986.html#fragment
