PUBLIC MARKS with tags javascript & performance

The HEAD section is the worst place to load scripts. It's painfully slow. The more and the bigger the worse it gets. Move scrips to the bottom and you run into dependency issues and you cannot safely use HTML5 and CSS3. Enter Head JS. A compact solution to these universal issues.

Enfin un schéma simple montrant la différence entre async, defer et rien

jQuery LazyLoad Ad

"With LABjs you can load your js files completely asynchronous."

"boomerang is a piece of javascript that you add to your web pages, where it measures the performance of your website from your end user's point of view"

JSLitmus is a lightweight tool for creating ad-hoc JavaScript benchmark tests.

LABjs (Loading And Blocking JavaScript) is an open-source (MIT license) project. on-demand JavaScript loader, capable of loading any JavaScript resource, from any location, into any page, at any time. LABjs by default will load (and execute) all scripts in parallel as fast as the browser will allow. However, you can easily specify which scripts have execution order dependencies and LABjs will ensure proper execution order. This makes LABjs safe to use for virtually any JavaScript resource, whether you control/host it or not, and whether it is standalone or part of a larger dependency tree of resources. It uses an expressive, chaining API to specify which scripts to load, and when to wait ("block"), if necessary, for execution before proceeding with further execution.

CSS expressions are a powerful (and dangerous) way to set CSS properties dynamically” … and … “The problem with expressions is that they are evaluated more frequently than most people expect”

"JavaScript Library CDNs use the network effect. Our survey of the Alexa 2000 shows that right now there are too few people in the network to get any value. Only Google’s AJAX Library API has anywhere near the penetration to provide any benefit"