Design & User Experience Topics
User experience design, frontend architecture, and design systems. Includes UX principles, accessibility, and design documentation.
User Interface and User Experience Design
Covers the principles and execution of designing intuitive, usable, and polished digital interfaces. Topics include visual design fundamentals such as layout, visual hierarchy, typography, color, spacing, and contrast; accessibility considerations including color contrast, keyboard navigation, labeling, and assistive technology support; component and pattern design for consistent reusable interfaces; form design, navigation, and information architecture that guide user flows; interaction design and microinteraction practices including states for hover, focus, active, disabled, loading, and error, as well as feedback patterns and motion to communicate system status; handling edge cases and error states gracefully; responsive and platform specific design considerations; prototyping, design to implementation handoff, and basic usability validation and metrics. Candidates should be prepared to explain design decisions, demonstrate familiarity with trade offs between aesthetics and usability, and discuss how interaction details improve task completion and user satisfaction.
State Management and Data Flow
Comprehensive coverage of strategies and patterns for managing application state and the flow of data in user interfaces and across system boundaries. Topics include local component state, derived state, and decisions about lifting state versus keeping it local; unidirectional data flow and event based updates; context providers and dependency injection for sharing state; and external state containers and libraries. Candidates should be able to explain criteria for selecting a solution based on application complexity, rendering performance, network characteristics, scalability, and team familiarity, and describe trade offs introduced by different libraries and architectures. Core engineering techniques include predictable state updates through immutability and pure update functions, minimizing duplicated and derived state, normalizing state shape, and designing for testability and debuggability. Synchronization concerns cover caching strategies and staleness models, when to refetch versus rely on cached data, optimistic and pessimistic update patterns and reconciliation, conflict resolution, and consistency across distributed front ends and server side systems. Also include considerations for rendering performance, concurrency, server side rendering, instrumentation, and debugging patterns used to reason about state in production.
Usability Testing and Validation
Comprehensive skills for planning, conducting, analyzing, and applying findings from usability studies to improve product ease of use and user satisfaction. Topics include defining clear research goals and success criteria, recruiting representative participants, writing neutral tasks and scenarios, and selecting appropriate methods and fidelity levels. Candidates should be able to choose and justify moderated versus unmoderated sessions, remote versus in person methods, and lab versus field testing, and to decide when to use low fidelity prototypes, high fidelity prototypes, or production interfaces. Coverage includes moderation and facilitation techniques, observational best practices such as think aloud protocols, strategies to reduce bias and demand effects, accessibility and cross device testing, and capturing both qualitative and quantitative data including task success, time on task, error rates, behavioral observations, and satisfaction measures. The topic also covers approaches to analyze and synthesize findings, triangulate qualitative insights with metrics, prioritize usability issues into actionable recommendations, create testable hypotheses, communicate results to stakeholders, plan iterative validation cycles, and integrate usability testing with other validation methods such as heuristic evaluation, analytics review, and split testing. Practical considerations such as sample size trade offs, session logistics, recording and consent, and tools for remote and unmoderated studies are also included.
Data Fetching and Client Patterns
Client side patterns for fetching and managing remote data in user facing applications. Coverage includes fetch versus library choices, handling loading and error states, request cancellation and abort controllers, concurrent requests and coordination, caching strategies, stale while revalidate and memoization, debouncing and throttling API calls, handling side effects in component lifecycles or hooks, use of observables or reactive streams for data flows, testing network interactions, and UX considerations for progressive loading and retries. Interviewers evaluate practical techniques to reliably fetch, display, cache and update remote data in front end and mobile clients.
Frontend Component and React Architecture
Covers component based frontend architecture and patterns with emphasis on React but applicable to component driven UI design generally. Topics include container versus presentational components, composition over inheritance, hooks, higher order components, render props, state management strategies, modularization, performance optimization, and testability. Candidates should explain how to decompose complex UIs into reusable, maintainable components and trade offs of different approaches.
Frontend Architecture and Client Side Performance
Understand modern frontend architectures including component-based design, state management patterns (Redux, MobX, Context API), server-state management vs. client-state management, and performance considerations. At Staff Level, go beyond framework details. Understand: virtual DOM and how it impacts performance, optimization techniques like code splitting, lazy loading, and tree-shaking, client-side routing and its implications for performance, progressive enhancement, and how to design APIs that minimize client-side work. Be comfortable discussing accessibility, performance metrics (LCP, CLS, FID), and how frontend decisions impact backend requirements (e.g., pagination vs. infinite scroll affects data loading patterns).
Frontend Performance Optimization
Comprehensive techniques and trade offs for improving client side performance in web applications and single page applications. Candidates should understand the browser rendering pipeline and critical rendering path including parsing, style calculation, layout, paint, and compositing, and how layout and paint costs produce reflow and repaint. They should know how component design and code patterns affect rendering and how to avoid layout thrashing and unnecessary re rendering. Candidates must be able to diagnose and mitigate JavaScript execution bottlenecks and long tasks that block the main thread using browser developer tools and performance application programming interfaces. Key topics include bundling and module strategies such as code splitting, lazy loading, tree shaking, and bundle size reduction; image optimization and responsive image techniques; network optimization including resource prioritization, compression, and caching strategies; service workers for offline capabilities and advanced caching patterns; and use of web workers to offload computation. Advanced considerations include virtual scrolling for large lists, progressive enhancement, server side rendering and client side rendering trade offs and hydration cost for universal applications, browser memory management and garbage collection implications, and how frontend decisions interact with backend constraints and overall system architecture. Candidates should also be familiar with measuring user experience using Core Web Vitals such as Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift, with real user monitoring and synthetic testing, and with establishing performance budgets and continuous performance monitoring.
Web Accessibility and User Experience
Building accessible UIs (WCAG compliance, semantic HTML, keyboard navigation, screen reader support). Understanding UX principles and how design impacts usability. Responsive design and mobile considerations. Understanding user feedback and iterating on UX.
Component State Management
Covers approaches and patterns for managing user interface state within component-based front end frameworks such as React and Angular. Topics include local component state, lifting state up, one way data flow, controlled versus uncontrolled components, prop passing and change handling, avoiding stale closures and missing dependency arrays, component composition patterns, performance considerations to prevent unnecessary re renders, and when to choose built in mechanisms versus external state libraries. For React this includes hooks such as useState, useContext, useReducer, useCallback, and useMemo and the trade offs of Context versus external stores. For Angular this includes using components and services, dependency injection, reactive programming patterns with observable streams, and change detection strategies. Candidates may be asked to compare state architectures, justify trade offs between simplicity and scalability, refactor components to improve state locality and performance, and design data flow for a feature from user interaction to persistent update.