jiagra: Javascript/Website Performance Enhancement

by Samy Kamkar, code@samy.pl 06/15/2011, http://samy.pl/jiagra

jiagra is a stand-alone javascript API for automatic website performance enhancement.

Currently features:

tracking timers/intervals to see if they've been fired or not window.checkTimeout(timeoutID) // returns 'active', 'fired', 'firedActive', 'cleared' or 'firedCleared' // active has never fired (interval or timeout) // cleared has never fired and been cleared (interval or timeout) // fired is a timeout that has fired // firedActive is an interval that has fired and still active // firedCleared is an interval that has fired and cleared
get a list (array) of timers that are either active, cleared or fired window.activeTimeouts() // active or firedActive window.clearedTimeouts() // cleared or firedCleared window.firedTimeouts() // fired, firedActive or firedCleared
clearInterval/clearTimeout now returns 'true' if cleared, 'false' if already cleared/fired, or undefined if no such timer Note that a timeout that is already 'fired' won't adjust to 'cleared'
document.currentScript polyfill + improvements over browser implementations Returns the script object which document.currentScript is getting called from. Unlike Opera/FF's built-in implementation, it will even work in callbacks and event handlers. It will also work on browsers which don't have a native implementation such as IE/Chrome/FF3.
prerendering/prefetching polyfill (pre-caching) for all browsers even if your browser doesn't support either.
John Resig's "degrading script tags", http://ejohn.org/blog/degrading-script-tags/ which now applies to ALL script tags on a page! // can be globally enabled/disabled, and individually enabled/disabled
<script src="path/to/script.js"> code() // this gets executed after script.js loads </script> <script src="path/to/script.js" data-degrade="true"> code() // this will run even if degradeEnabled is turned off </script> <script src="path/to/script.js" data-degrade="false"> code() // this will NOT run </script>

Currently, it contains a pseudo-polyfill for pre-rendering/pre-fetching, improved document.currentScript polyfill for determining the script tag that's being executed, advanced timeout/interval functions and degrading script tags,

Timeout/interval functions: these functions allow advanced setting, monitoring, clearing and checking of timeouts/intervals, even if executed from other scripts you don't control.

Pre-rendering/pre-fetching: This allows the page to load/cache files you expect the user to be accessing, such as the next link. Using actual browser prerendering is only supported in a handful of bleeding-edge browsers, however this polyfill should work in any browser! This allows pages to be pre-cached by the browser and ready to load as soon as the user clicks, specifically determined by the website maintainer (or smarty-pants code that figures out which pages are accessed most).

INSTALLATION:

Simply add the script to your page like so:

Then add pre-render/pre-fetch links to any URLs you want ready ASAP:

That's it!

Read more about Chrome Prerendering: http://code.google.com/chrome/whitepapers/prerender.html

Read more about Firefox Prefetching: https://developer.mozilla.org/en/Link_prefetching_FAQ

Jiagra

Install / Use

README