A JR frontend developer is a professional who works on the visual, design and interaction aspects of an application. It is responsible for creating and styling web pages, menus, buttons, forms and other elements that users see and interact with. He is also responsible for ensuring the usability, accessibility and compatibility of the application.

A JR frontend developer can do several tasks, such as:

- Develop, test and maintain the frontend code of an application using technologies such as HTML, CSS, JavaScript, etc.;

- Create and apply layouts, colors, fonts, images, icons and animations to give personality and identity to the application;

- Create and implement interactive elements, such as menus, buttons, forms, sliders, etc., to facilitate navigation and application functionality;

- Use version control tools, such as Git, to manage source code and collaborate with other developers;

- Use automated testing and code quality tools to verify code appearance, behavior and compliance;

- Use frontend frameworks and libraries, such as Bootstrap, React, Angular, Vue, etc., to facilitate development and increase productivity;

- Use agile methodologies, such as Scrum and Kanban, to organize teamwork and deliver value to the customer;

- Learn and apply emerging technologies, such as responsive design, progressive web apps, web components, etc., to improve the user experience on different devices and platforms.