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React Nested Checkbox Tree (Parent–Child Sync)

By FrontendAtlas Team · Updated Jan 30, 2026

Build a small React UI that renders a parent checkbox and multiple child checkboxes. The parent controls all children, and the children keep the parent in sync (checked, unchecked, or indeterminate). React focus: compute parent indeterminate state from child selections. Framework focus: React hooks (useState/useEffect),…

Render a parent checkbox with a label, plus several child checkboxes listed…
Checking the parent selects all children.

What you’ll build / What this tests

This premium react coding focuses on React Nested Checkbox Tree (Parent–Child Sync). You’ll apply react and state thinking with intermediate level constraints. The prompt emphasizes Build a small React UI that renders a parent checkbox and multiple child checkboxes. The parent….

Learning goals

Translate the prompt into a clear react API signature and return shape.
Apply react, state, event-handlers techniques to implement react nested checkbox tree (parent–child sync).
Handle intermediate edge cases without sacrificing readability.
Reason about time/space complexity and trade-offs in react.

Key decisions to discuss

Define the exact input/output contract before coding.
Prioritize predictable edge-case handling over micro-optimizations.

Evaluation rubric

Correctness: covers required behaviors and edge cases.
Clarity: readable structure and predictable control flow.
Complexity: avoids unnecessary work for large inputs.
API discipline: no mutation of inputs; returns expected shape.
Testability: solution is easy to unit test.

Constraints / Requirements

Render a parent checkbox with a label, plus several child checkboxes listed under it.
Checking the parent selects all children.
Unchecking the parent clears all children.
When children are toggled individually:
- If all are checked → parent is checked.
- If none are checked → parent is unchecked.
- If some are checked → parent is indeterminate.
Keep everything in a single component.
Each child checkbox toggles independently.
The parent reflects the aggregate state of the children.

Mini snippet (usage only)

// Example usage
const input = /* react nested checkbox tree (parent–child sync) input */;
const result = solve(input);
console.log(result);

// Edge case check
const empty = input ?? null;
const fallback = solve(input);
console.log(fallback);

// Expected: describe output shape, not the implementation
// (no solution code in preview)

Common pitfalls

Mutating inputs instead of returning a new value.
Skipping edge cases like empty input, duplicates, or nulls.
Overlooking time complexity for large inputs.