in priciple an Ionic app is an angular app. Ionic 3 provides some tooling.
So you do not work directly with the angular cli, instead you use the ionic cli like ionic serve. Also Ionic 3 provides components, directives and wrappers for native plugins.
So you can use any angular (not angularjs) tutorials to see how it works on html side and how it communicates with/from ts side. An often read advice is, do not manipulate dom by yourself, use the concepts of angular.
A complete tutorial is https://angular.io/tutorial
Often it is for a beginner easier to fllow tutorials shorter tutorials like Josh Moronys tutorials.
Most of js is valid ts. ts transpiles all to js. So you can use js in typescript. Better is learning typescript, it is not so much. https://www.typescriptlang.org/docs/home.html
For example on ts you should use let instead of var, as long as you need var explict.
an example on html side
<button ion-button (click)='alertme()'><button>
is the html element, ion-button is a directive, (click) describes the event handler and alertme() is the methode that is called on ts side.
On ts side you have for example
Best regards, anna-liebt