ReactJS Program to Star Rating State with Explanation
ReactJS
Medium
State Management
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1 min read
89 words
This problem helps you practice core ReactJS fundamentals in a practical way. It builds intuition around rating, star, state. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Build a 5-star rating component where user can select a rating.
Input Format
No input.
Output Format
Render a React component.
Constraints
Store selected rating in state and render stars from it.
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
import React, { useState } from 'react';
function Star({ filled, onClick, label }) {
return (
<button type='button' onClick={onClick} aria-label={label} style={{ width: 40, height: 40, borderRadius: 12, border: '1px solid #ddd', background: filled ? '#eafaf1' : '#fff', color: filled ? '#0b5' : '#999', fontSize: 18 }}>
★
</button>
);
}
export default function App() {
const [rating, setRating] = useState(0);
return (
<div style={{ padding: 16 }}>
<h2 style={{ marginTop: 0 }}>Rate meetcode</h2>
<div style={{ display: 'flex', gap: 8 }}>
{Array.from({ length: 5 }, (_, i) => {
const value = i + 1;
return <Star key={value} filled={value <= rating} onClick={() => setRating(value)} label={'Rate ' + value} />;
})}
</div>
<div style={{ marginTop: 10, color: '#555' }}>Selected: {rating || 'None'}</div>
</div>
);
}
Output Example
No sample I/O is provided for this question.
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
Build a 5-star rating component where user can select a rating.
Input / Output
Output
Render a React component.
Constraints
Store selected rating in state and render stars from it.
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Difficulty
Medium
ReactJS
Official Solution
import React, { useState } from 'react';
function Star({ filled, onClick, label }) {
return (
<button type='button' onClick={onClick} aria-label={label} style={{ width: 40, height: 40, borderRadius: 12, border: '1px solid #ddd', background: filled ? '#eafaf1' : '#fff', color: filled ? '#0b5' : '#999', fontSize: 18 }}>
★
</button>
);
}
export default function App() {
const [rating, setRating] = useState(0);
return (
<div style={{ padding: 16 }}>
<h2 style={{ marginTop: 0 }}>Rate meetcode</h2>
<div style={{ display: 'flex', gap: 8 }}>
{Array.from({ length: 5 }, (_, i) => {
const value = i + 1;
return <Star key={value} filled={value <= rating} onClick={() => setRating(value)} label={'Rate ' + value} />;
})}
</div>
<div style={{ marginTop: 10, color: '#555' }}>Selected: {rating || 'None'}</div>
</div>
);
}
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