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- AMD
- ###
- .. toctree::
- :maxdepth: 2
- Overview
- ========
- There are two JavaScript system in Elgg: the deprecated 1.8 system, and the newer `AMD (Asynchronous Module
- Definition) <http://requirejs.org/docs/whyamd.html>`_ compatible system introduced in 1.9.
- This discusses the benefits of using AMD in Elgg.
- Why AMD?
- ========
- We have been working hard to make Elgg's JavaScript more maintainable and useful.
- We made some strides in 1.8 with the introduction of the "``elgg``" JavaScript object and library, but
- have quickly realized the approach we were taking was not scalable.
- The size of `JS on the web is growing
- <http://httparchive.org/trends.php?s=All&minlabel=Feb+11+2011&maxlabel=Feb+1+2013#bytesJS&reqJS>`_
- quickly, and JS in Elgg is growing too. We want Elgg to be able to offer a solution that makes JS
- development as productive and maintainable as possible going forward.
- The `reasons to choose AMD <http://requirejs.org/docs/whyamd.html>`_ are plenteous and
- well-documented. Let's highlight just a few of the most relevant reasons as they relate to Elgg
- specifically.
- 1. Simplified dependency management
- -----------------------------------
- AMD modules load asynchronously and execute as soon as their dependencies are available, so this
- eliminates the need to specify "priority" and "location" when registering JS libs in Elgg. Also, you
- don't need to worry about explicitly loading a module's dependencies in PHP. The AMD loader (RequireJS in this
- case) takes care of all that hassle for you. It's also possible have
- `text dependencies <http://requirejs.org/docs/api.html#text>`_ with the RequireJS text plugin,
- so client-side templating should be a breeze.
- 2. AMD works in all browsers. Today.
- ------------------------------------
- Elgg developers are already writing lots of JavaScript. We know you want to write more. We cannot
- accept waiting 5-10 years for a native JS modules solution to be available in all browsers before
- we can organize our JavaScript in a maintainable way.
- 3. You do not need a build step to develop in AMD.
- --------------------------------------------------
- We like the edit-refresh cycle of web development. We wanted to make sure everyone developing in
- Elgg could continue experiencing that joy. Synchronous module formats like Closure or CommonJS just
- weren't an option for us. But even though AMD doesn't require a build step, *it is still very
- build-friendly*. Because of the ``define()`` wrapper, it's possible to concatenate multiple modules
- into a single file and ship them all at once in a production environment. [#]_
- AMD is a battle-tested and well thought out module loading system for the web today. We're very
- thankful for the work that has gone into it, and are excited to offer it as the standard solution
- for JavaScript development in Elgg starting with Elgg 1.9.
- .. [#] This is not currently supported by Elgg core, but we'll be looking into it since reducing round-trips is critical for a good first-view experience, especially on mobile devices.
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