[Devel] Mark-as-read via javascript and cookies

[Chris Dolan]

On Dec 14, 2004, at 8:26 AM, Jeff Waugh wrote:

> <quote who="Chris Dolan">
>
>> Yesterday I noodled with a solution to allow visitors to my Planet 
>> mark
>> items as read via javascript.
>
> Sweet baby jebus.
>
> - Jeff (taking some time to digest)

Thanks, Jeff.  I'll take that as a compliment.  :-)

To forestall some comments, I'll point out an implementation detail and 
an associated bug.  The javascript stores the marked items in a cookie 
in a compact format to avoid the 4K limit on cookie data.  This format 
is:
   top: ID of first story during the last visit
   list: comma-separated list of zero-based indices of marked stories 
relative to the "top" story

So, on my planet right now the top story is 
"http://www.macrumors.com/pages/2004/12/20041214094914.shtml".  If I 
mark that story as read, and the third, fourth and eighth story down as 
well, my cookie will read
   top=http://www.macrumors.com/pages/2004/12/20041214094914.shtml
   list=0,2-3,7

This relies on the critical assumption that the order of stories always 
remains fixed, and that new stories are only added to the top of the 
list.  That is true for most Planets.  However, when you add a new feed 
to your Planet, stories may be inserted into the "past" if your 
"new_feed_items" config is non-zero.  This would lead to the wrong 
stories being flagged as read.  Therefore, if you employ my 
mark-as-read feature into your Planet, I suggest you set 
"new_feed_items=0" as a workaround to this issue.

Chris
--
Chris Dolan, Software Developer, www.chrisdolan.net
Public key: http://www.chrisdolan.net/public.key
Planet: http://www.chrisdolan.net/planet/
Arch repository: chris at chrisdolan.net--2004
Arch mirror: http://www.chrisdolan.net/arch/
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