Custom Elements / Shadow Root in DART lang vs Shadow Root in JavaScript - dart

Question

I've the this Shadow Element/root in this example http://jsfiddle.net/fyf6thte/8/ working perfectly with JavaScript, interested to have similar one with DART, so I wrote the below code (using the same html and css file), but I could not see the button it looks theshadow.innerHTML = '<button id="d">click</button>'is not working
the full code is:
import 'dart:html';
void main() {
var thehost = document.querySelector('#host1');
document.registerElement(fonixDiv.tag, fonixDiv);
thehost.append(new fonixDiv());
}
class fonixDiv extends HtmlElement {
static final tag = 'fonix-div';
var shadow;
bool disabled;
factory fonixDiv() => new Element.tag(tag);
fonixDiv.created() : super.created() {
shadow = this.createShadowRoot();
shadow.host.innerHTML = '<button id="d">click</button>';
shadow.host.onClick.listen((e){
this.host.dataset.disabled='true'; // set Attribute to the custom element
});
shadow.children.d.onClick.listen((e){
this.text = "you clicked me :(";
// or shadow.children[0].textContent="Shadow DOM content changed";
this.disabled=true;
// alert("All: button, text and host should be change");
});
}
#override
void attached() {
super.attached();
this.disabled=disabled;
}
}
I'm not sure about the accuracy of the balance of the code, I can check it only after I see the button.
any help.

Answer 1

The error is correct: in Dart 'this' is not bound contextually as in JS and instead we have lexical scoping;
in your dart code you are actually changing the text content of the custom element and not of the target of the event (the button in the shadow root). So basically you have a custom element, you set the text content on it but you also have a shadow root created inside of that same DOM node and it shadows everything else you put inside that custom element and that is why you do not see it and continue to see the shadow root's content - this is how shadow root works by design.
To fix it you need to update the text content (and the disabled property) on the button (for example e.target.text = ...).
Hope this helps.

Answer 2

Seems like the .host should be removed from this line
shadow.host.innerHTML = '<button id="d">click</button>';
shadow.innerHTML = '<button id="d">click</button>';
The jsfiddle doesn't have it and it seems weird. I think with .host you add it basically to this and therefore as child not as content.

Answer 3

I think the main issue is: Use innerHtml instead of innerHTML.
There are a few additional minor things you need to fix:
Remove 'host', as Gunter says, you want to set the innerHtml of the shadow.
Instead of shadow.children.d.onClick, do shadow.querySelector('#d').onClick.
Also, do dataset['disabled'] instead of dataset.disabled.