As for what you are saying, yes, $obj[0] is the way to pass in the context, as you shouldn’t really pass in a jQuery object* and by indexing, you are getting the html node which is what will really speed things up

* now if you pass in a jQuery object it can seem faster, but that is because you are doing a more specific selector on the sizzle engine rather than using a context.

Remember:


$(’a', ‘#myContainer’).context; // => document


becomes:


$(’#myContainer’).find(’a');


It would be interesting to see some metrics on all this, but I’m up to my eyeballs in coding at the mo!

So let’s say you have:

var $obj = $('#myContainer');

I think what you’re saying is that it’s more efficient to do:

$('a', $obj[0]);

rather than:

$('a', $obj);

Is that right? (And thanks again for chiming in here – I’m a dork for JS performance )

Another way of coding it (from Brandon’s site)

”
// get the node for the context
var context = $(‘#myContainer’)[0];

// pass the context as the second argument
$(‘a’, context).context; // =>
“

But that’s news to me on being able to pass document.getElementById(‘blah’) to the jQuery context, seems like that could be useful. Do you have any idea whether it is better performance-wise to do that rather than $('blah').find('blah')?

Nice article, just a little catch on the context syntax,

Recommend you look at Brandon Aaron’s latest blog entry:
http://brandonaaron.net/

To quote:

”
$(‘a’, ‘#myContainer’).context; // => document

When jQuery encounters another selector for the context it actually converts it to say the following instead.

$(‘#myContainer’).find(‘a’);
”

To set the context you would either get the html element for #myContainer by indexing the jquery wrapped set and passing that in, or more preferably IMO do:

$(‘a’, document.getElementById(‘myContainer’));

Nice article though