ReactJS Program to Window Width Listener with Explanation
ReactJS
Medium
Hooks & Effects
29 views
1 min read
87 words
This problem helps you practice core ReactJS fundamentals in a practical way. It builds intuition around window, width, listener. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Show window width and update it on resize using an effect.
Input Format
No input.
Output Format
Render a React component.
Constraints
Add resize listener and remove it on cleanup.
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
import React, { useEffect, useState } from 'react';
export default function App() {
const [w, setW] = useState(() => window.innerWidth);
useEffect(() => {
function onResize() {
setW(window.innerWidth);
}
window.addEventListener('resize', onResize);
return () => window.removeEventListener('resize', onResize);
}, []);
return (
<div style={{ padding: 16 }}>
<strong>meetcode responsive</strong>
<div style={{ marginTop: 8, fontSize: 24, fontWeight: 800 }}>{w}px</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
Show window width and update it on resize using an effect.
Input / Output
Output
Render a React component.
Constraints
Add resize listener and remove it on cleanup.
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, { useEffect, useState } from 'react';
export default function App() {
const [w, setW] = useState(() => window.innerWidth);
useEffect(() => {
function onResize() {
setW(window.innerWidth);
}
window.addEventListener('resize', onResize);
return () => window.removeEventListener('resize', onResize);
}, []);
return (
<div style={{ padding: 16 }}>
<strong>meetcode responsive</strong>
<div style={{ marginTop: 8, fontSize: 24, fontWeight: 800 }}>{w}px</div>
</div>
);
}
Solutions (0)
No solutions submitted yet. Be the first!
