Optimizing : constructing a jquery collection

Question

I have this Jquery code that construct a collection of jquery objects. It takes around 600 ms to execute. I want to optimize it:

var tousBt = $('img.boutonReduire');
var stack = $('');
tousBt.each( function() {
    var id = $(this).attr('id');
    stack = stack.add('#table' + id).add('#img' + id);
  });

Do you see something that I can do ? The result has to be a collection of jquery objects.

Edit: I get all the stacks elements and hide them : stack.addClass('hideit'); There is around 125 elements. And $('*').length give around 7100 elements.

Answer 1

First and foremost, remove the assignment operation inside your iteration function. stack is an instance---there's no need to reassign it:

var tousBt = $('img.boutonReduire');
var stack = $('');
tousBt.each( function() {
    var id = $(this).attr('id');
    stack.add('#table' + id).add('#img' + id);
});

I'd also suggest getting away from jQuery overhead if you're calling add() a tons of times. Here's a version using a lightweight array to accumulate the selectors:

var tousBt = $('img.boutonReduire');
var stack = [];
tousBt.each( function() {
    var id = this.id;
    stack.push('#table' + id);
    stack.push('#img' + id);
});

Then, to get the finalized selector that you can use with jQuery:

var selector = stack.join(','); 
//$(stack.join(','));

Edit: this may seem absolutely retarded, but this might actually be fastest (worth a shot at least):

var tousBt = $('img.boutonReduire');
tousBt.each(function() {
    var id = this.id;
    $('#table' + id).addClass('selected');
    $('#img' + id).addClass('selected');
});
var stack = $('.selected');