Re: [Edbrowse-dev] $ object in javascript

[Kevin Carhart <kevin@carhart.net>]

Hi Karl and company,

$.get is a wrapper around an HTTP get.  So the page code loads a version 
of jquery, which includes a get method someplace within it.  When the page 
code calls this, it will want to work with XMLHttpRequest supplied by the 
DOM.  So it goes to our XMLHttpRequest code in startwindow, or should. 
>From there, it calls our native method for inline HTTP requests, in 
jseng-moz.cpp.  It can 
then fire the request, get some html, send it back to startwindow, and 
from startwindow send it back to the page's code.  When it says

function (data) { ...

, this is a handler that specifies what it will do with the HTML 
that is returned.  It could do particular DOM splices, put the response 
into a div, or stuff like that.  I am not sure if it is formally correct 
to call it a callback, but that's the idea.

So the pieces are there, but it has not been exercised 
that much.  When I was trying to get the drescher site working, it was a 
cycle like this and in some cases it worked.  So the good news is that 
the intentions of this snippet represent a common thing to want to do, so 
effort we put into it will pay off.

Here's a paraphrase of the entire snippet.  Yes, as Chris says, the $ is 
just an alias for the jQuery object.  It tests for the presence of a 
certain table which is subsidiary to the node scheduled_top15s.  If not 
found... if (not ( blah blah expression has length) ...

you go grab it inline, using GET, 
and once you have it, you follow the instructions in the handler, so in 
this case it populates the innerhtml of scheduled_top15s with the 
dynamically retrieved tags.  And our native C++ will handle 
this, which is very cool!

At this point, whatever code follows can rely on that thing existing 
because you either verified its presence or grabbed it using GET.


>
> if(!$("#scheduled_top15s").find("table").length){
> $.get("php/get_scheduled_top15s_public_2.php", function( data ) {
>  $("#scheduled_top15s").html( data );
> });
> }
>