Develop Smart Event Handlers
How developing Smart Event Handlers improves Web site download performance
Sometimes pages feel less responsive because of too many event handlers attached to different elements of the DOM tree which are then executed too often. That's why using event delegation is a good approach. If you have 10 buttons inside a div, attach only one event handler to the div wrapper, instead of one handler for each button. Events bubble up so you'll be able to catch the event and figure out which button it originated from. You also don't need to wait for the onload event in order to start doing something with the DOM tree. Often all you need is the element you want to access to be available in the tree. You don't have to wait for all images to be downloaded. DOMContentLoaded is the event you might consider using instead of onload, but until it's available in all browsers, you can use the YUI Event utility, which has an onAvailable method. For more information check the YUI theatre's "High Performance Ajax Applications" by Julien Lecomte.
Other Topics
Overview Web Site performance Improvement Minimize HTTP Requests Use a Content Delivery Network Add an Expires or a Cache-Control Header Gzip Components Put Stylesheets at the Top Put Scripts at the Bottom Avoid CSS Expressions Make JavaScript and CSS External Reduce DNS Lookups Minify JavaScript and CSS Avoid Redirects. Remove Duplicate Scripts Configure ETags Make Ajax Cacheable Flush the Buffer Early Use GET for AJAX Requests Post-load Components Preload Components Reduce DOM Elements Split Components Across Domains Minimize the Number of iframes No 404s Reduce Cookie Size Use Cookie-free Domains for Components Minimize DOM Access Develop Smart Event Handlers Choose over @import Avoid Filters Optimize Images Optimize CSS Sprites Don't Scale Images in HTML Make favicon.ico Small and Cacheable Keep Components under 25K Pack Components into a Multipart Document Avoid Empty Image src
