Adding Javascript to Add and Edit Forms based on behavior

1

I would like to add some javascript to both my Add and Edit forms only if a behavior marker is present.

Good docs here https://docs.plone.org/external/plone.app.dexterity/docs/advanced/custom-add-and-edit-forms.html and here https://training.plone.org/5/javascript/exercises/2.html

Also, this javascript should be included if a behavior is enabled. For this example, the javascript file can contain alert("script is present"); and is registered as a javascript resource. See docs above in how to register a js resource.

The edit form was easy - the trick is to set the browser view for to the behavior instead of the type:

   <browser:page
    name="edit"
    for=".behaviors.IJavascriptBehavior"
    class=".browser.EditView"
    permission="cmf.ModifyPortalContent"
    />

file .browser:

from Products.CMFPlone.resources import add_resource_on_request
from plone.dexterity.browser import edit
class EditView(edit.DefaultEditForm):

    def __call__(self):
        # utility function to add resource to rendered page
        add_resource_on_request(self.request, 'MyJavascriptResource')
        return super(EditView, self).__call__()

The add form, however, I can't seem to make work with ONLY THE BEHAVIOR - I have to set it for all add forms (for the 'story' portal type). It registers to the FTI - but how to I isolate it to a behavior?

Python is simple enough:

class AddView(add.DefaultAddView):

def __call__(self):
    # utility function to add resource to rendered page
    add_resource_on_request(self.request, 'MyJavascriptResource')
    return super(AddView, self).__call__()

But the ZCML is quite different:

   <adapter
    for="Products.CMFCore.interfaces.IFolderish
         zope.publisher.interfaces.browser.IDefaultBrowserLayer
         plone.dexterity.interfaces.IDexterityFTI"
    provides="zope.publisher.interfaces.browser.IBrowserPage"
    factory=".browser.AddView"
    name="story"
   />
   
   <class class=".browser.AddView">
    <require
        permission="cmf.AddPortalContent"
        interface="zope.publisher.interfaces.browser.IBrowserPage"
        />
   </class>

I thought replacing 'IFolderish' with my behavior would work, but even the docs say 'you must not do this' and it doesn't work.

Maybe a layer? But I don't want to get into the whole 'most specific layer' problem even if it does work.

Any thoughts or experience you can share?