Angular two-way binding for the open attribute of the details HTML5 tag.
You'll need to add it as a dependency of your module, like this:
angular.module("yourModule", [..., "detailsOpenBinding"])
Then add the js file in index.html (or load it however else you like), and finally use it as in the following sample.
<details open-binding="someFieldOnTheScope">
<summary>foo</summary>
More foo...
</details>