javascript 64 lines · 8 steps

Building a dual-thumb price slider in React

A two-handle range slider that keeps its min and max from ever crossing, using clamped state updates.

Explained by highlit
React Intermediate controlled-components state-clamping usecallback form-inputs
1import { useCallback, useState } from "react";
2 
3const MIN = 0;
4const MAX = 1000;
5const GAP = 50;
6 
7export default function PriceRangeSlider({ onChange }) {
8 const [range, setRange] = useState({ min: 200, max: 800 });
9 
10 const updateMin = useCallback((value) => {
11 setRange((prev) => {
12 const next = Math.min(Math.max(value, MIN), prev.max - GAP);
13 const updated = { ...prev, min: next };
14 onChange?.(updated);
15 return updated;
16 });
17 }, [onChange]);
18 
19 const updateMax = useCallback((value) => {
20 setRange((prev) => {
21 const next = Math.max(Math.min(value, MAX), prev.min + GAP);
22 const updated = { ...prev, max: next };
23 onChange?.(updated);
24 return updated;
25 });
26 }, [onChange]);
27 
28 const toPercent = (value) => ((value - MIN) / (MAX - MIN)) * 100;
29 
30 return (
31 <div className="range-slider">
32 <div className="range-slider__track">
33 <div
34 className="range-slider__fill"
35 style={{
36 left: `${toPercent(range.min)}%`,
37 right: `${100 - toPercent(range.max)}%`,
38 }}
39 />
40 </div>
41 <input
42 type="range"
43 min={MIN}
44 max={MAX}
45 value={range.min}
46 onChange={(e) => updateMin(Number(e.target.value))}
47 className="range-slider__thumb range-slider__thumb--min"
48 aria-label="Minimum price"
49 />
50 <input
51 type="range"
52 min={MIN}
53 max={MAX}
54 value={range.max}
55 onChange={(e) => updateMax(Number(e.target.value))}
56 className="range-slider__thumb range-slider__thumb--max"
57 aria-label="Maximum price"
58 />
59 <output className="range-slider__values">
60 ${range.min} – ${range.max}
61 </output>
62 </div>
63 );
64}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Clamping values inside the state updater keeps two dependent handles from crossing each other.
  2. 2Deriving both handles from one state object keeps the min and max always consistent.
  3. 3Optional-chaining a callback lets a component report changes without requiring the parent to supply a handler.

Related explainers

javascript 
class LyricsSync {
  constructor(audio, container, lines) {
    this.audio = audio;
    this.container = container;

Building a synced lyrics highlighter

binary-search dom-manipulation event-handling
Intermediate 9 steps
javascript 
const express = require('express');
 
const app = express();
 

Enforcing HTTPS with Express middleware

middleware https security
Intermediate 6 steps
javascript 
const express = require('express');
const router = express.Router();
 
router.get('/articles/:slug', async (req, res, next) => {

Conditional GET caching in Express

http-caching conditional-get routing
Intermediate 8 steps
javascript 
function parseHexColor(hex) {
  const cleaned = hex.trim().replace(/^#/, '');
 
  const expand = (short) =>

Parsing hex colors into RGBA channels

parsing bitwise regex
Intermediate 7 steps
javascript 
import { useReducer, useCallback } from 'react';
 
function historyReducer(state, action) {
  const { past, present, future } = state;

Undo/redo form state with a React reducer

undo-redo reducer immutability
Intermediate 10 steps
javascript 
import { NextResponse } from 'next/server';
import { db } from '@/lib/db';
 
function csvCell(value) {

Streaming a CSV export in a Next.js route

streaming csv readablestream
Advanced 9 steps

Share this explainer

Here's the card — post it anywhere.

Building a dual-thumb price slider in React — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code