Question

I have a grid and there is a column which contains <a> anchor tag with some additional information in <data-..> tag and has a class name <class='myspeciallink'>. And in my unobtrusive JS script I select all the elements with that class name and apply live('click'). I need that to be live() because the grid gets generated in the runtime.

What happens inside the live('click') handler? I use that additional data and add a <div> to the page based on that data. Which in its turn used to generate jQuery UI dialog. It works great on my computer.

But! How could that work in real-world? Should I be bothered about possible performance implications? I feel that applying live() on more than a dozen elements instantaneously
would affect the performance. Especially with rather complicated handler like mine – it needs to get the data, parse the data, create a div, apply a dialog and etc.

Does that smell like a bad design? Could you suggest a different approach or my concerns are unfounded? Can I use some sort of a profiler tool to find the bottlenecks in my javascript?

UPD: Still nobody suggested any profiling tool. firebug and chrome dev tools are good, but maybe there is something even better?

Answer 1

live("click") is actually better up-front from a performance standpoint: Instead of binding an event handler to each matched element, you’re applying a single event handler which waits for events to bubble up and then sees if the element that triggered the event matches the selector .live was called on.

Compare this to $('selector').click(...) which does loop over each element and bind a new event handler. live('click') has no additional overhead regardless of how many page elements match its selector. Depending on how many elements your selector matches, using .live can avoid a delay of up to a few seconds during the initial load of each page.

However, the event handler must check each event which bubbles up against its selector, to see if there is a match. This is going to add a small amount of overhead to every click event, but chances are very good that your users will not notice the difference.