From Messy to Modular: Rebuilding Filters in React

Why It Matters

The redesign cuts developer overhead and delivers a consistent, shareable filtering experience across CI, CD and other modules, boosting productivity and product reliability.

Key Takeaways

• Legacy filters caused hidden UI and state loss.
• Context API decouples filters, improves type safety.
• URL parser syncs typed values with query strings.
• Central FiltersMap stores value, query, and state.
• Inversion of Control enables flexible, reusable filter framework.

Pulse Analysis

Modern web applications often struggle with complex UI state, especially when filters must be discoverable, shareable and performant. Harness’s legacy filtering suffered from hidden drawers, inconsistent behavior across modules, and lost state on page refresh, creating friction for developers and end‑users alike. By rethinking the component architecture, the team addressed these pain points head‑on, laying a foundation that scales as product modules grow.

The core of the new solution is React’s Context API, which supplies filter state and actions to any child component via a custom hook. This eliminates prop‑drilling and the costly React.cloneElement anti‑pattern, while preserving strict TypeScript typing. A dedicated parser interface translates between rich JavaScript types and URL strings, enabling seamless two‑way synchronization: every filter change updates the URL for bookmarkability, and URL changes rehydrate the UI instantly. All active filters live in a centralized FiltersMap, storing both the typed value and its serialized query, reducing redundant parsing and improving render performance.

For engineering teams, the approach delivers tangible benefits: adding a new filter requires only a component file, no framework modifications. Inversion of Control lets the parent application dictate data fetching and analytics, keeping the filter library agnostic and reusable across pipelines, services, and repositories. This pattern exemplifies best practices for scalable front‑end state management, offering a blueprint that other SaaS products can adopt to enhance user experience and accelerate development cycles.