Senior Frontend Engineer (React and Ext JS Hybrid) $$$$

In a partnership with a global consulting company we are seeking a versatile Senior Frontend Engineer to join our team and contribute to a large-scale, modular enterprise product.

Our ecosystem is in an active phase of evolution: while our core system is built on Sencha Ext JS (7.5+), we are strategically introducing React for new functional modules and high-performance UI components. The ideal candidate is a "bridge-builder"—an engineer who can navigate both frameworks, leveraging the power of modern React and the Carbon (Client Design System) while maintaining and optimizing our robust Ext JS foundation. The client is a British multinational enterprise software company.

Key Responsibilities

• Modern Feature Development: Build and scale new application modules using React (Hooks, Context API, and modern state management).
• Design System Implementation: Integrate Carbon (Sage Design System) to ensure consistent, accessible, and high-quality user interfaces.
• Enterprise Maintenance: Maintain and enhance existing enterprise modules built with Sencha Ext JS 7.5+ (Classic toolkit) using MVVM architecture.
• Hybrid Integration: Ensure seamless interaction and data flow between React-based components and the existing Ext JS environment.
• UI/UX Translation: Transform complex designs from Figma into responsive layouts using modern CSS (Flexbox, Grid, SASS).
• Performance Optimization: Profile and optimize data-heavy components and complex views across both frameworks.
• Collaborative Engineering: Work closely with backend teams (consuming RESTful APIs/JSON) and QA to deliver high-quality, maintainable code.

Required Skills & Experience

• React Mastery: 3+ years of professional experience with React and its modern ecosystem (Hooks, State Management).
• Ext JS Expertise: Solid experience with Sencha Ext JS (6.5+ / 7.5+), with a strong understanding of component inheritance, stores, models, and the MVVM/MVC lifecycle.
• Core Fundamentals: High proficiency in JavaScript (ES6+), object-oriented design, asynchronous programming, and advanced debugging.
• Modern Styling: Experience with Carbon or similar enterprise UI frameworks; deep knowledge of HTML5, CSS3, and SASS.
• Data Architecture: Proven track record of integrating with RESTful APIs and managing complex state in enterprise-scale applications.
• Workflow: Confidence using Git, package managers (NPM/Yarn), and modern build tools (Webpack/Vite).

Nice to Have

• Experience with TypeScript for large-scale application development.
• Familiarity with Ext JS theming and custom SASS/Compass theme development.
• Domain background in ERP, HRM, or HCM systems with complex user workflows.
• Knowledge of unit testing frameworks like Jest and React Testing Library.