JavaScript dependency manager with magical powers
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Javascript dependency manager with magical powers

##Not So Quick and Dirty Tour Pt1.

###AMD This branch contains the AMD compatible version of i.js. This means the CommonJS 'define()' syntax can be used:

define('FOO', [', FOO.baz'], function(bar, baz) {
	// The top level FOO{} object now exists
	FOO.isAwesome = true;
	// bar and baz have been passed in as args. They would have been
	// scripts that provide and FOO.baz. Notice how we have
	// shortened the names. This is possible because the args are just
	// references to the actual objects so call them whatever you want
	FOO.doStuff = function() {
	// Scripts that provide a namespace should return a value that will
	// be passed to others that require it. Here we return the FOO{} object
	// that we declared
	return FOO;

The first argument to the 'define' method is the namespace you are providing, the second is an Array (must be an Array) of one or more Strings that must be the provided namespace of other scripts you are using as dependencies. The third is a function which will be called once all listed dependencies have been loaded (AND thier callbacks called).

####The Anonymous define(...) Your script doesn't have to provide a namespace, you could just list dependencies and provide a callback:

define(['bar, baz'], function(bar, baz) {

You can't require such a script anywhere else as it doesn't provide anything. Which brings me to my next topic...

#####Currently Unsupported Use Of The Anonymous define(...) The current AMD spec states that an anonymous define(), one which doesn't provide a module 'id' as the first argument (like the one above), should use the filename as the module id. While this is a straightforward task for the depwriter to do, it is not so for the various client-side environments. I don't feel it is efficient to write quite a bit of extra code just so a developer can skip explicitly identifying a module. Therefore examples such as this:

	foo: 'bar',
	baz: function(a) {
		//do stuff...

Are not supported and i.js will throw an error. This example will work however:

define('', {
	baz: 'quux',
	spam: function(a) {
		//do stuff...

The difference is in the explicit statement of a module id as the first argument. Also unsupported would be this:

define(function() {});

However this:

define('foo', function() {
	// do stuff...

Will work just fine (useful for class constructors).

###require() This method is used to load a provided dependency when a full define() statement is not needed. A typical use-case is seen in the example site in this repo where require() is used on the index.html page.


the dependency test.js provides TEST and depwriter.rb would have mapped those for you already.

####Caveat Don't put define(...) statements on non *.js files. I have explored this quite a bit and decided that it is much more efficient to reserve them for actual modules (your site's javascript files). Allowing define statements on .html or other template pages would have added code to the callback listening mechanism i.js employs. The require() statement is much better suited for this.

A common use case is having a single require('FOO') statement in which the loaded 'foo.js' module is acting as a bootstrap, or main type of script.

###cache One of a two methods that now are prefixed and suffixed with double underscores (a la' Python magic methods). These methods are globals that are not part of the AMD spec but are important aspects of the i.js API.

cache will fetch and store a script in the browser cache without injecting a tag and parsing it. See this for a little background on 'preloading'. This allows you to control your page load times even more as you can cache scripts which may be needed later, such as those that are needed in response to a particular user action.

Also, cache is particularly useful for jQuery plugins in an async environment where you need to make sure jQuery itself is fully ready before injecting the plugin script tags

cache expects a single argument, either a string or arrays of strings that resolve to provided namespaces of other scripts. For example look at the test.js file in this repo:


###parse The counterpart to cache, this method expects two args. The first, same as cache is a string or array of strings that represent other dependencies. The second is a callback that will be executed once the cached dependencies have been loaded. This is essentially the same as the anonymous define that gives an array of dependencies and a callback. The advantage of using parse is that is explicitly states in code that you are injecting tags for scripts that have been preloaded

###config.yaml All your configuration settings should go here now. Take a look at the source file itself as it's commented fairly extensively.

###Demaximizer You can set the config file's demaximize boolean to true to tell i.js to create a minified version of your files (excluding cdn and third-party files) and reference those instead of the non-minified versions. By default the 'min_suffix' is set to '.min' (also in the config.yaml) which will result in a file named 'foo.min.js' in the same directory as a file named 'foo.js'. The generated script tags will then point to 'foo.min.js'.

Setting the 'demaximize' flag back to false will simply change the script tags source attribute back to the non-minified file (make sure to run depwriter again).

As with the auto-generated deps.js file you don't have to worry about these, i.js takes care of them for you. Just go about developing your site then set the demaximize flag to true when you are ready to move to production.

###Depwriter.rb A utility program that scans your project directory looking for dependencies, files with define() and require() depending on setting in the config.yaml file. Depwriter.rb produces the deps.js file that simply registers dependencies with i.js by name and path. This saves i.js from the inefficient task of having to resolve paths at runtime.

See the docs and examples for usage.

###Deps.js One of 2 files that you include in your documents head, along with i.js itself. The deps.js file is an auto-generated file that you don't have to worry about. While developing your site you will run depwriter.rb after making changes and this file will be produced.

###Don't Ask Me Try the included test-page example for yourself.

##Not So Quick And Dirty Pt.2