A JavaScript/jQuery developer designs, implements, and tests web applications using JavaScript language and jQuery library. They write reusable code, optimize applications for speed and scalability, and ensure technical feasibility of UI/UX designs. They create interactive features that enhance user experience, like dynamic web content and animations. They troubleshoot and fix bugs, and maintain code quality through best practices. They collaborate with other developers, designers, and stakeholders, and stay updated with modern JavaScript libraries and tools. They may also be responsible for integrating front-end elements with server-side logic, and ensuring cross-browser compatibility.