Hybrid Mobile Apps have taken the development scene by storm. Before this, Developers had to learn native app languages to develop, which at times had an incredibly high learning curve. However with hybrid frameworks, it will make mobile app development faster and easier. Most of the frameworks use JS, besides HTML/CSS.
Ionic is also a completely free and open-source framework which makes use of AngularJS for creating highly interactive apps. All you need to do is install the node and get started.