A Full-stack JavaScript Engineer is proficient in both backend and frontend development, ensuring a seamless user experience. They can handle all aspects of development, from server and database management to user interface design. They are experienced in JavaScript and its frameworks like Node.js, React.js, and Angular.js, which are essential for modern, interactive web applications. Hiring such a professional can streamline your project, increase efficiency, and reduce costs associated with hiring separate frontend and backend developers. They can also ensure better coordination and communication, leading to a more cohesive end product.