Middle Front-End Developer with React.js
On-site · Warsaw, Mazovia, Poland or Lisbon, Lisbon, Portugal
Job Summary
Middle Front-End Developer with React.js sought to modernize legacy jQuery applications into React, build new React apps, and ensure high performance and quality. Responsibilities include migrating and refactoring jQuery-based applications to React, developing new React applications with component-driven design, maintaining and optimizing code for speed and scalability, collaborating with UX/UI designers and back-end developers, writing unit and integration tests, using Git workflows, mentoring junior developers, and documenting development processes and coding standards.
Required Qualifications
- Proven experience (2-4 years) as a front-end developer with a focus on JavaScript, React, and jQuery
- Expert knowledge of JavaScript (ES6+), including core concepts like closures, promises, asynchronous programming, and module bundling
- Strong experience with React (class-based and functional components, hooks, state management) and a solid understanding of component-driven development
- Solid understanding of jQuery and experience migrating or maintaining legacy jQuery codebases
- Familiarity with modern JavaScript tools and libraries such as Webpack, Babel, NPM, and ES6+ syntax
- Experience with RESTful APIs and asynchronous programming (fetch, axios, etc.)
- Strong knowledge of front-end HTML5, CSS3, and responsive design principles
- Experience with version control systems, particularly Git
- Understanding of front-end performance optimization techniques (e.g., lazy loading, code splitting, tree shaking)
- Good understanding of web security practices and accessibility standards
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