Question

Just out of curiosity, I’m wondering how gmail does what it does. After looking in the source of the page you don’t see any links, onclick methods and javascript. I understand they hide the javascript, but still the page knows that there was a click. Is there a daemon thread running that listens for your clicks? How does it work??

Answer 1

A bit old now but here’s an article kind of explaining Gmail under the hood: http://johnvey.com/features/gmailapi/ (see section “About the Gmail engine and protocol”)

The item most relevant to this project
is what I refer to as the “DataPack”,
a base HTML file that contains only
JavaScript array declarations that the
UI engine parses and then uses to
determine what to update. The
advantages of this should be
immediately obvious: reduced traffic
load, and increased functionality —
especially for developers who no
longer have to resort to crude “screen
scraping” techniques to interface with
web applications. Although the ideal
situation for external developers
would be an XML-based DataPack, the
JavaScript version is sufficient (and
I suspect it was chosen for
performance reasons as well).

The DataPack format consists of
individual “DataItems”, or JavaScript
arrays wrapped in a envelope function.
An example:

D(["ts",0,50,106,0,"Inbox","fd36721220",154]);

Wikipedia’s entry is pretty good at a brief overview too: http://en.wikipedia.org/wiki/Gmail_interface