A Full Stack JavaScript Developer is a software developer who specializes in using JavaScript to build both the front-end (client-side) and back-end (server-side) components of web applications. They have expertise in various JavaScript technologies and frameworks, allowing them to work on the entire stack of a web application. Here are the key skills and technologies commonly associated with a Full Stack JavaScript Developer:

Front-End Skills:

1. HTML/CSS: Proficiency in HTML for structuring web content and CSS for styling and layout.
2. JavaScript: Strong knowledge of JavaScript, including ES6 (ECMAScript 2015) and later versions, for adding interactivity and dynamic behavior to web pages.
3. Front-End Frameworks: Experience with front-end frameworks like React, Angular, or Vue.js for building user interfaces efficiently.
4. Responsive Design: Ability to create responsive layouts using CSS media queries to ensure web applications are mobile-friendly.
5. UI/UX Design: Understanding of user interface (UI) and user experience (UX) design principles to create user-friendly interfaces.
6. AJAX: Proficiency in making asynchronous requests to the server using AJAX (Asynchronous JavaScript and XML) or Fetch API.
7. Web Accessibility: Knowledge of web accessibility standards (WCAG) to make web applications accessible to all users, including those with disabilities.

Back-End Skills:

1. Server-Side JavaScript: Proficiency in using JavaScript on the server-side with technologies like Node.js.
2. Web Frameworks: Familiarity with Node.js frameworks like Express.js for building scalable and efficient back-end services.
3. Database Management: Experience with both relational databases (e.g., MySQL, PostgreSQL) and NoSQL databases (e.g., MongoDB) for data storage and retrieval.
4. API Development: Ability to design, build, and maintain RESTful APIs (Application Programming Interfaces) for communication between the front-end and back-end.
5. Authentication and Authorization: Implementing user authentication and access control mechanisms to secure web applications.
6. Server Management: Understanding of server deployment, configuration, and management using tools like Docker, Kubernetes, or cloud platforms like AWS, Azure, or Google Cloud.
7. Security Best Practices: Knowledge of security measures and best practices to protect web applications against common vulnerabilities.
8. Testing and Debugging: Conducting unit testing, integration testing, and debugging to ensure the reliability and quality of the back-end code.
9. Version Control: Proficiency in using Git for code versioning and collaboration with other developers.
10. Caching: Implementing caching strategies to optimize web application performance.
11. Serverless Computing: Familiarity with serverless architecture for building scalable and cost-effective applications.