javascript 55 lines · 7 steps

Building an accessible star-rating widget

A vanilla-JS class renders interactive stars and keeps hover, selection, and ARIA state in sync through a single paint method.

Explained by highlit
Intermediate dom event-handling accessibility state-management ui-components
1class StarRating {
2 constructor(container, { max = 5, value = 0, onChange } = {}) {
3 this.container = container;
4 this.max = max;
5 this.value = value;
6 this.hovered = 0;
7 this.onChange = onChange;
8 this.render();
9 this.bindEvents();
10 }
11 
12 render() {
13 this.container.classList.add('star-rating');
14 this.container.innerHTML = Array.from({ length: this.max }, (_, i) =>
15 `<span class="star" data-index="${i + 1}" role="radio" tabindex="0" aria-label="${i + 1} star">\u2605</span>`
16 ).join('');
17 this.stars = [...this.container.querySelectorAll('.star')];
18 this.paint();
19 }
20 
21 bindEvents() {
22 this.stars.forEach((star) => {
23 const index = Number(star.dataset.index);
24 star.addEventListener('mouseenter', () => {
25 this.hovered = index;
26 this.paint();
27 });
28 star.addEventListener('click', () => this.select(index));
29 star.addEventListener('keydown', (e) => {
30 if (e.key === 'Enter' || e.key === ' ') {
31 e.preventDefault();
32 this.select(index);
33 }
34 });
35 });
36 this.container.addEventListener('mouseleave', () => {
37 this.hovered = 0;
38 this.paint();
39 });
40 }
41 
42 select(index) {
43 this.value = this.value === index ? index - 1 : index;
44 this.paint();
45 this.onChange?.(this.value);
46 }
47 
48 paint() {
49 const active = this.hovered || this.value;
50 this.stars.forEach((star, i) => {
51 star.classList.toggle('filled', i < active);
52 star.setAttribute('aria-checked', String(i + 1 === this.value));
53 });
54 }
55}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Routing every visual update through one paint method keeps hover and selection state consistent without scattered DOM writes.
  2. 2Building interactive DOM from a data array lets index metadata drive both rendering and event logic.
  3. 3Adding role, tabindex, and aria-checked makes a custom widget usable by keyboard and screen readers.

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