ondomready | AMD compatible module to detect when the DOM | Frontend Framework library

I have a custom Wicket Behaviour (RegisterBehaviour) which can be attached to various Wicket components to add multiple JaveScript-Snippets event handlers to them via a (OnDomReady-)HeaderItem in RegisterBehaviour.renderHead(Component, IHeaderResponse).

Now I have the requirement to trigger one of these events right after the page has been loaded to initialise all components with a certain computed value. To do that, I thought could add another Wicket Behaviour (TriggerBehaviour) which generates the approriate JaveScript-Snippet.

My problem is though, that the JaveScript-Snippet generated by this TriggerBehaviour would have to be run after the JaveScript-Snippets of all the RegisterBehaviour on a page and in all components have been run. I know that HeaderItems can have dependencies but this mechanism seems to target the case, when I want some kind of common library loaded (like jQuery) or code executed before my custom code. To use this for my case, I'd have to somehow find all RegisterBehaviours on the fly that are being added to the current render phase of the page and dynamicly add them as dependencies to the TriggerBehaviour, so they run before the TriggerBehaviours JavaScript. I see no way though, how to get such a list of all HeaderItems of a certain type.

Any tips on how to approach this problem, either in Wicket or JavaScript?

(Using Java 8 and Wicket 8.9.0)

I have this ajax call that populate the fields to a related field.

I have a simple dropdown menu which looks like this:

I am working with canvas, right now I can save into DB and I can change the background image to one I choose of a image list.

My problem is when I tried to save the canvas with the background the saved image just show me the draw but doesn't the image background...can somebody help me with this?

Best Regards!

Here the code:

I'm working on a pretty big project and have managed to get everything working on most all browsers except for MS Edge. No supprise there but I really need this hover effect to work. The hover event triggers once in Edge and then stops working entirely. In addition, it never even calls the function I set up. I have watered down the basic function and related code, made a demo and included it here as well as setting up a jsfiddle here: https://jsfiddle.net/8cqw60Le/4/. Almost forgot, I'm running Windows 10 fully updated, the code is running Jquery 3.2.0 and it's setting up on "onDomready" though nothing else I tried worked either. Please help. I'm stumped.

html: