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Build a File Explorer (tree view)

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01

Understand the problem

Build a collapsible folder/file tree from nested data.

ReactTreeRecursion
02

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Building a File Explorer (tree view) in React

Mental model: A file system is a tree of nodes (type: 'folder' | 'file', optional children). Render it recursively. Folders toggle open/closed; files are leaves. Track expanded folders in a Set of ids so the open/closed state survives re-renders without mutati

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04

React solution

Complete solutionRun Playground
import React from 'react';
import FileExplorer from './src/FileExplorer';

const tree = {
  id: 'root',
  name: 'project',
  type: 'folder',
  children: [
    {
      id: 'src',
      name: 'src',
      type: 'folder',
      children: [
        { id: 'app', name: 'App.js', type: 'file' },
        { id: 'idx', name: 'index.js', type: 'file' },
        {
          id: 'comp',
          name: 'components',
          type: 'folder',
          children: [
            { id: 'btn', name: 'Button.js', type: 'file' },
            { id: 'card', name: 'Card.js', type: 'file' },
          ],
        },
      ],
    },
    { id: 'pkg', name: 'package.json', type: 'file' },
    { id: 'readme', name: 'README.md', type: 'file' },
  ],
};

export default function App() {
  return (
    <div style={{ fontFamily: 'sans-serif', padding: 20 }}>
      <h1>File Explorer Demo</h1>
      <FileExplorer tree={tree} />
    </div>
  );
}
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