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JSXmain.jsx

14px

import React, { useState, useEffect } from 'react';

export default function App() {
  const [count, setCount] = useState(0);
  const [history, setHistory] = useState([]);

const handleIncrement = () => {
    const next = count + 1;
    setCount(next);
    setHistory(prev => [...prev.slice(-4), next]);
  };

const handleDecrement = () => {
    const next = count - 1;
    setCount(next);
    setHistory(prev => [...prev.slice(-4), next]);
  };

const handleReset = () => {
    setCount(0);
    setHistory([]);
  };

return (
    <div style={{
      maxWidth: 440,
      margin: '20px auto',
      background: '#1e293b',
      border: '1px solid #334155',
      borderRadius: 16,
      padding: 28,
      textAlign: 'center',
      boxShadow: '0 20px 40px rgba(0,0,0,0.35)',
      color: '#f8fafc'
    }}>
      <div style={{
        display: 'inline-block',
        padding: '4px 12px',
        borderRadius: 20,
        background: 'rgba(6, 182, 212, 0.15)',
        color: '#06b6d4',
        fontWeight: 800,
        fontSize: '0.8rem',
        marginBottom: 16
      }}>
        ⚛️ React 19 Live Playground
      </div>

<h2 style={{ fontSize: '1.4rem', fontWeight: 800, marginBottom: 8 }}>
        Interactive Counter Component
      </h2>
      <p style={{ color: '#94a3b8', fontSize: '0.9rem', marginBottom: 20 }}>
        Full Stack Learning Simplified — State &amp; Hooks Demo
      </p>

<div style={{
        fontSize: '3rem',
        fontWeight: 800,
        color: count > 0 ? '#34d399' : count < 0 ? '#f87171' : '#38bdf8',
        margin: '16px 0',
        fontFamily: 'monospace'
      }}>
        {count}
      </div>

<div style={{ display: 'flex', gap: 10, justifyContent: 'center', marginBottom: 20 }}>
        <button
          onClick={handleDecrement}
          style={{
            background: '#334155',
            color: '#fff',
            border: 'none',
            borderRadius: 8,
            padding: '10px 18px',
            fontSize: '1rem',
            fontWeight: 700,
            cursor: 'pointer'
          }}
        >
          - Decrement
        </button>

<button
          onClick={handleReset}
          style={{
            background: 'transparent',
            color: '#94a3b8',
            border: '1px solid #475569',
            borderRadius: 8,
            padding: '10px 14px',
            fontSize: '0.9rem',
            cursor: 'pointer'
          }}
        >
          ↺ Reset
        </button>

<button
          onClick={handleIncrement}
          style={{
            background: 'linear-gradient(135deg, #06b6d4, #3b82f6)',
            color: '#fff',
            border: 'none',
            borderRadius: 8,
            padding: '10px 18px',
            fontSize: '1rem',
            fontWeight: 700,
            cursor: 'pointer'
          }}
        >
          + Increment
        </button>
      </div>

{history.length > 0 && (
        <div style={{ fontSize: '0.8rem', color: '#64748b', borderTop: '1px solid #334155', paddingTop: 12 }}>
          Recent values: {history.join(' → ')}
        </div>
      )}
    </div>
  );
}

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Write modern React 19 components with hooks (useState, useEffect, useMemo) and inspect the interactive result live with responsive viewport switching.

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Interactive State with useState

function Counter() {
  const [count, setCount] = React.useState(0);
  return (
    <button onClick={() => setCount(c => c + 1)}>
      Clicked {count} times
    </button>
  );
}

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❓Frequently Asked Questions about Online React.js Compiler

Can I preview my React component on Mobile and Tablet screen sizes?▲

Yes! Use the Desktop (🖥️), Tablet (📱), and Mobile (📱) buttons above the preview pane to test responsive component layouts.

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⚡ Online React.js Compiler

⚛️

Live In-Browser React 19 Sandbox & Preview

Write modern React 19 components with hooks (useState, useEffect, useMemo) and inspect the interactive result live with responsive viewport switching.

⚡

Instant Zero-Setup Execution

Run code immediately in your browser with zero downloads, installation, or environment setup.

⌨️

Interactive Standard Input (stdin)

Full support for interactive scanners, terminal arguments, and multi-line user inputs.

🤖

AI Error Diagnosis & 1-Click Fixes

Get instant What • Why • How error explanations and auto-apply fixes directly into your editor.

🔗

1-Click Code Sharing

Generate instant shareable URLs to collaborate with teammates, classmates, or instructors.

⚡ Online React.js Compiler

Live In-Browser React 19 Sandbox & Preview

Ready to Master React.js? Learn with Structured Lessons

React 19 Complete Guide

Next.js 16 Full-Stack Masterclass

📖React.js Quick Syntax Reference

❓Frequently Asked Questions about Online React.js Compiler

⚡ Online React.js Compiler

Live In-Browser React 19 Sandbox & Preview

Ready to Master React.js? Learn with Structured Lessons

React 19 Complete Guide

Next.js 16 Full-Stack Masterclass

📖React.js Quick Syntax Reference

❓Frequently Asked Questions about Online React.js Compiler