@Fedik just saw this PR now.

It seems like a very good idea.
Is the PR this still valid?

If so, some questions:

• will this allow adding inline js/css with dependencies too?
• does this allow to add other attributes (e.g. data attributes) to the script or link tag?
• will this allow to add specific css/js with conditional statements (IE)?
• with changes in the document rendering, will it be possible to define the asset HTML render position (ex: head tag, before end of body tag)

Drawbacks

• it make a bit more complicated the development entry point
• I need to write joomla.asset.json, but it is also the Advantage, as I do not need to write my custom behavior helper
• it is to complicated if I really want add just a single file

For what i understand, and please correct if i'm wrong, if want to add a jquery dependent js script (without adding a json file), we'll do this:

$jsAsset = new JAssetItem('myCustomAsset')->setDependency(array('jquery'))->setJs(array('myjsfile.js'));
JHtml::_('asset.load', $jsAsset);

And now we use something like this:

JHtml::_('jquery.framework');       
JHtml::_('script', 'myjsfile.js');

So actually we can add it with the same lines of code (and without json). But yes, is not simple as the current method.

But if this is merged we can in the future modify the addScript (and other script css related methods) to use this to generate the css/js assets, right?

Is the PR this still valid?

it do not have a conflicts, so I guess it is valid

will this allow adding inline js/css with dependencies too?

It only for files, however if we allow "custom class" for each asset https://github.com/joomla/joomla-cms/pull/8913/files#diff-5dbc66d167ed44e3946ee1a79efb5201R574 then the class can have some own logic for add inline css/jss when JAssetFactory::attach() will be called

Also there #6357 is additional idea for reduce to zero the inline js.

• does this allow to add other attributes (e.g. data attributes) to the script or link tag?
• will this allow to add specific css/js with conditional statements (IE)?
• with changes in the document rendering, will it be possible to define the asset HTML render position

The Asset factory it is just a layer over, it does not do more than JDocumentHtml allow to do. See JAssetItem::attachCss and JAssetItem::attachJs

But if this is merged we can in the future modify the addScript (and other script css related methods) to use this to generate the css/js assets, right?

Nope, the reason the same, it just a layer
My very naive idea is do not use addScript/addStyleshet directly, in future

.. if want to add a jquery dependent js script

yes, you can do as in your example,
or you can make a joomla.asset.json for your extension and place it under media/com_blabla/joomla.asset.json. Then in the code you can add one of your asset by:

JHtml::_('asset.load', 'my-cool-asset-name');

And AssetFactory automatically will load all css/js dependencies.

Also this allow to reuse your asset by other extensions, easily ... in theory

it do not have a conflicts, so I guess it is valid

Since it was travis errors i thought it was "abandoned" :)

I think the concept is very good, and i understand that now we can only use what JDocument allows.
But i think having the possibility to manage all assets (inline or not) through here would be nicer.

If with this we could implement a component with js/css files, inline js/css, dependencies, data-* attributes, async, defer, etc using only Asset factory layer (one to rule then all :) ) i think it would be more easy and logic to everyone, than using a bunch of different methods, ex: JHtml (script, stylesheet, asset), addScript, addScriptVersion, addStyleSheet, etc.

But i think having the possibility to manage all assets (inline or not) through here would be nicer.

With assets I mean only files, here.
Example you use colorbox: the library contain colorbox.js and colorbox.css - that the "colorbox" asset.
And the inline code for init the library it is not "asset" .. cause it can be very different, depend from case.

However you can make one more asset for your extension with "behavior-colorbox.js" (see other pull request) with "colorbox" as dependency, and putt there all code that will handle data-*, and do other stuf that need for your extension.

Well I am bad in good explanation

ok, this is only for external js/css files. I understand why, but from a developer learning curve perspective don't you agree with me that can be rather confusing having so many methods for js/css inline external, versioning, etc?

well, yes .. learning is hard here, can be ...
Maybe I try add some proxy for addXXXDeclaration, in to JHtmlAsset, so all will be in the one place.

So after all it can looks like:
Before
for 'some-library':

JHtml::_('behavior.core');
JHtml::_('jquery.framework');
JHtml::_('stylesheet', 'extension/some-library.css', false, true);
JHtml::_('script', 'extension/some-library.js', false, true);
$doc->addScriptDeclaration('some init code');

It not hard if I have it in single layout, but a bit annoying if need to edit it in couple different layouts.
I know about JHtml Behaviors, but it hard to manage the dependencies.

After
joomla.asset.json:

{
    "title" : "Some Extension",
    "name"  : "com_someextension",
    "author": "my name",
    "assets": [
        {
            "name": "some-library",
            "version": "1.0.0",
            "versionAttach": true, // attach the version query to each file
            "js": [
                "com_someextension/some-library.min.js"
            ],
            "css": [
                "com_someextension/some-library.css"
            ],
            "dependency": [
                "core",
                "jquery"
            ]
        },
    ]
}

and in layout just:

JHtml::_('asset.scriptDeclaration', 'alert("blabla")', $deps = array('some-library'));

hm

yes, it seems good. or for just jquery dependency something like this.

$inlineJs = '$( document ).ready(function() { alert("blabla"); });';
JHtml::_('asset.scriptDeclaration', $inlineJs, array('jquery'));

or for vanilla js without dependencies something like this.

JHtml::_('asset.scriptDeclaration', 'alert("blabla");');

I have added:

JHtml::_('asset.scriptDeclaration', $content, $dependancy); // Adds an inline script to the page
JHtml::_('asset.styleDeclaration', $content, $dependancy); // Adds an inline style declaration to the page

And now the AssetFactory pick up joomla.asset.json from the template to (see example for Isis and Protostar, in this pull request)

Any word on this?

Sadly it cannot be synced easily (more easy to write new). I kept it open to get some feedback, but seems not much interest in it.
I planed to make "basic" version of this patch for J 4.x, maybe some day.

I am closing it,
if someone interesting, can keep discussion in the related topic #12402