jQuery bind efficiency

Question

I'm having issue with load speed using multiple jQuery binds on a couple thousands elements and inputs, is there a more efficient way of doing this?

The site has the ability to switch between product lists via ajax calls, the page cannot refresh. Some lists have 10 items, some 100, some over 2000. The issue of speed arises when I start flipping between the lists; each time the 2000+ item list is loaded the system drags for about 10 seconds.

Before I rebuild the list I am setting the target element's html to '', and unbinding the two bindings below. I'm sure it has something to do with all the parent, next, and child calls I am doing in the callbacks. Any help is much appreciated.

loop 2500 times

<ul>
  <li><input type="text" class="product-code" /></li>
  <li>PROD-CODE</li>
  ...
  <li>PRICE</li>
</ul>

end loop

$('li.product-code').bind( 'click', function(event){ 

    selector = '#p-'+ $(this).prev('li').children('input').attr('lm');

        $(selector).val(

            ( $(selector).val() == '' ? 1 : ( parseFloat( $(selector).val() ) + 1 ) )

        );

    Remote.Cart.lastProduct = selector;
    Remote.Cart.Products.Push( 

            Remote.Cart.customerKey, 
            { 
                code      : $(this).prev('li').children('input').attr('code'),
                title     : $(this).next('li').html(), 
                quantity  : $('#p-'+ $(this).prev('li').children('input').attr('lm') ).val(), 
                price     : $(this).prev('li').children('input').attr('price'),
                weight    : $(this).prev('li').children('input').attr('weight'),
                taxable   : $(this).prev('li').children('input').attr('taxable'),
                productId : $(this).prev('li').children('input').attr('productId'),
                links     : $(this).prev('li').children('input').attr('productLinks')
            },
            '#p-'+ $(this).prev('li').children('input').attr('lm'),
            false,
            ( parseFloat($(selector).val()) - 1 )

    );

    return false;

});

$('input.product-qty').bind( 'keyup', function(){ 

    Remote.Cart.lastProduct = '#p-'+ $(this).attr('lm');
    Remote.Cart.Products.Push( 

            Remote.Cart.customerKey, 
            { 
                code      : $(this).attr('code') , 
                title     : $(this).parent().next('li').next('li').html(), 
                quantity  : $(this).val(), 
                price     : $(this).attr('price'),
                weight    : $(this).attr('weight'),
                taxable   : $(this).attr('taxable'),
                productId : $(this).attr('productId'),
                links     : $(this).attr('productLinks')
            },
            '#p-'+ $(this).attr('lm'),
            false,
            previousValue
    );
});

Answer 1

You are binding a handler 2500 times, instead make your function use either live or delegate like this:

$('li.product-code').live('click', function(event){ 
$('input.product-qty').live('keyup', function(){ 

.live() listens for the click to bubble up at the DOM level then executes the event with the context of the click source. This means you have one event handler instead of 2500 of them, meaning it's much faster and easier on the browser.

If you have a container that wraps the replaced content that isn't replaced (remains across all AJAX calls), you can make it more local like this:

$('#container').delegate('li.product-code', 'click', function(event){ 
$('#container').delegate('input.product-qty', 'keyup', function(){ 

The result of this is the event bubbles fewer times before being caught.

Another pain point is probably the creation of the elements, can you post that code? There are often easy optimizations that yield a big performance boost there.

Update

As of jQuery 1.7, the .live() method is deprecated. Use .on() to attach event handlers. Users of older versions of jQuery should use .delegate() in preference to .live() - JQuery Docs

Answer 2

Bind your click event to the entire document, and within the function, look at event.target to see which product element was actually clicked on. This way you only need to do a single bind.