UI/UX Personal Blog

To prevent JavaScript from blocking page loading, we recommend using the HTML async attribute when loading JavaScript. For example: <script async src="my.js"> If your JavaScript resources use document.write, it is not safe to use asynchronous loading. We recommend that scripts that use document.write be rewritten to use a different technique. Additionally, when loading JavaScript asynchronously, if your page loads scripts that depend on one another, care must be taken to make sure that your application loads scripts in the proper dependency order. If the external scripts are small, you can include them directly into the HTML document. Inlining small files in this way allows the browser to proceed with rendering the page.

Yahoo's Exceptional Performance team has identified 34 rules that affect web page performance. YSlow's web page analysis is based on the 23 of these 34 rules that are testable. Click each performance rule below to see the details. Minimize HTTP Requests Use a Content Delivery Network Avoid empty src or href 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 Use GET for AJAX Requests Reduce the Number of DOM Elements No 404s Reduce Cookie Size Use Cookie-Free Domains for Components Avoid Filters Do Not Scale Images in HTML Make favicon.ico Small and Cacheable