Hi @rahulb31017943,
For SPA, while using front-end technologies like REACT or ANGULAR, we do not use HTML or sightly to render the content. Instead, we create a component using REACT or ANGULAR.
To read the values in the dialog, we use the sling model exporter. Check an example here. Even though the blog gives a REACT example, it is more or less the same for angular as well.
Hope this helps.
Thanks,
Kiran Vedantam.