An developer designs and implements user interface components for JavaScript-based web and mobile applications using the framework. They are responsible for combining the art of design with programming, translating UI/UX design wireframes into actual code that produces the visual elements of the application. They also ensure high performance on mobile and desktop environments, conduct comprehensive testing, and troubleshoot to maintain product quality. Additionally, they collaborate with other team members and stakeholders, and participate in the full development life cycle, including concept, design, build, deploy, test, and release to app stores.