Frontend Developer

Level: Middle Frontend Developer with practical experience building production web applications.

Required skills: Modern JavaScript (ES6+), TypeScript, React functional components and Hooks, React Query, Zustand, and styled-components, with basic knowledge of HTTP, the DOM, RESTful APIs, and the JavaScript event loop.

Familiar tasks: Developing features for existing web funnels and single-page applications, implementing web-to-app flows, and integrating analytics, A/B testing, and payment systems; experience with no-code or low-code UI builders is a plus.

How do React functional components and Hooks improve the maintainability of a single-page application?

Functional components keep UI logic composable, while Hooks allow state, side effects, and reusable behavior to be organized into focused custom Hooks. This reduces lifecycle complexity and makes components easier to test and maintain.

How would you use React Query and Zustand together in a web2app flow?

React Query would manage server state such as API data, caching, synchronization, and mutations. Zustand would manage local client state such as the current funnel step, form values, UI flags, and temporary user selections.

How would you design an efficient data-fetching strategy for a React funnel?

I would identify which data can be prefetched, define stable query keys, configure appropriate stale times, and handle loading, error, and retry states explicitly. Mutations should invalidate or update related queries to keep the UI consistent.

How does TypeScript improve a frontend application that integrates RESTful APIs?

TypeScript provides compile-time validation for component props, API request parameters, and response models. I would define shared interfaces or schemas and avoid unsafe assumptions by handling optional, nullable, and unexpected response fields.

How would you structure styled-components to keep styles modular and maintainable?

I would colocate styles with their components, extract reusable visual primitives, and use theme variables for colors, spacing, and typography. Component props should control variants in a predictable way without duplicating CSS rules.

How would you implement A/B testing in an existing web funnel?

I would assign users to variants deterministically, persist the assignment when necessary, and ensure both variants share clear analytics events. The implementation should prevent layout or content flicker and allow experiments to be disabled safely.

What considerations are important when integrating analytics into a single-page application?

Analytics events should be emitted for meaningful user actions rather than incidental renders, with a consistent naming and payload convention. I would also account for route changes, duplicate events, consent requirements, and failures in the analytics provider.

How would you implement a payment flow on the frontend?

I would keep payment-sensitive operations on the backend, use the provider’s secure client-side SDK where applicable, and treat the backend response as the source of truth. The UI should clearly handle pending, success, cancellation, and failure states without exposing secrets.

What happens in the JavaScript event loop when an asynchronous operation completes?

Synchronous code runs on the call stack, while callbacks are queued after asynchronous work completes. Promise callbacks run in the microtask queue, which is processed before the next macrotask such as a timer or user event.

How would you optimize the performance of a React-based web funnel?

I would measure first, then apply techniques such as code splitting, lazy loading, memoization where justified, optimized images, and minimizing unnecessary renders. I would also avoid excessive client-side data fetching and monitor Core Web Vitals.

Gismart is a global mobile app developer with over 1 billion downloads, creating products across Health & Wellness, Utilities, and Music. As a Frontend Developer, you’ll build web funnels and single-page web2app experiences, integrating analytics, A/B testing, and payment systems. The stack includes modern JavaScript, TypeScript, React, React Hooks, React Query, Zustand, and styled-components; this is a full-time, fully remote role with a flexible schedule, while the salary is not disclosed. Apply to make a global impact from anywhere, with generous health and learning benefits, coworking support, equipment coverage, and strong growth opportunities.