How would you implement a multi-select dropdown with search in React?

🧩 Scenario

Build a reusable MultiSelect component that:

• Allows selecting multiple options shown as tags
• Filters options via search input with debounce
• Supports keyboard navigation and tag removal with Backspace
• Virtualizes options for large datasets
• Loads options asynchronously

🧠 Answer (Design Overview)

Core Design

1. Controlled vs Uncontrolled: Expose both APIs; default to controlled.
2. Option API: Options are { value, label }.
3. Search & Debounce: Debounce input and support server-side filtering.
4. Selected Tags: Render selected items as removable tags with a max visible count.
5. Virtualization: Use react-window for long lists inside dropdown.
6. Keyboard: Arrow up/down to navigate, Enter to select, Backspace to remove last tag.

Tradeoffs:

• Virtualization requires measuring dropdown height and item size.
• Async loading adds complexity but necessary for big datasets.

🎮 Live Demo: Multi-Select Dropdown

🔍 Real-World Tips

• For 100k+ options, fetch server-side using pagination and virtualize results.
• Limit visible tags and show "+N more" for compactness.
• Use aria attributes (combobox, listbox, option) for accessibility.

Quick Practice

1. Add keyboard navigation and Backspace to remove last tag.
2. Replace options with an async loader.
3. Integrate react-window for option virtualization.

Summary

• Multi-selects need a balance of UX (tags), performance (virtualization), and accessibility.
• Debounce searches and prefer server-side filtering for large datasets.