@accesslint/core

Pure accessibility rule engine for WCAG auditing. 84 bundled rules and zero browser dependencies.

Highlights

- Lightweight — 31 KB gzipped (IIFE), with zero runtime dependencies
- Chunked audits — time-budgeted processing via createChunkedAudit to avoid long tasks on the main thread
- ESM, CJS, and IIFE — tree-shakable ES modules, CommonJS for Node, and a single-file IIFE for script injection into any page
- Runs anywhere — works with happy-dom, jsdom, and real browsers with no DOM polyfills or compatibility workarounds. Run accessibility audits in Vitest and React Testing Library using the same environment as the rest of your tests
- MIT licensed

Install

``sh
npm install @accesslint/core
`

Quick start

$3

Audit a rendered component in your existing test suite:

`tsx
import { render } from "@testing-library/react";
import { runAudit } from "@accesslint/core";
import { LoginForm } from "./LoginForm";

test("LoginForm has no accessibility violations", () => {
const { container } = render();
const { violations } = runAudit(container.ownerDocument);
expect(violations).toEqual([]);
});
`

$3

Inject the library into the page and audit the live DOM:

`ts
// a11y.spec.ts
import { test, expect } from "@playwright/test";

const iife = require.resolve("@accesslint/core/iife");

test("page has no accessibility violations", async ({ page }) => {
await page.goto("https://example.com");

await page.addScriptTag({ path: iife });

const violations = await page.evaluate(() => {
const { runAudit } = (window as any).AccessLintCore;
return runAudit(document).violations.map(
(v: any) => ({ ruleId: v.ruleId, message: v.message, selector: v.selector, impact: v.impact })
);
});

expect(violations).toEqual([]);
});
`

$3

Inject the library into the page and audit the live DOM:

`js
// cypress/e2e/a11y.cy.js
Cypress.Commands.add("audit", () => {
return cy
.readFile("node_modules/@accesslint/core/dist/index.iife.js")
.then((src) => {
return cy.window().then((win) => {
win.eval(src);
const result = win.AccessLintCore.runAudit(win.document);
return result.violations;
});
});
});

describe("sample.html accessibility audit", () => {
beforeEach(() => {
cy.visit("sample.html");
});

it("has no accessibility violations", () => {
cy.audit().should("have.length", 0);
});
});
`

API

$3

Run all active rules against a document and return violations.

`ts
interface AuditResult {
url: string;
timestamp: number;
violations: Violation[];
ruleCount: number;
}

interface Violation {
ruleId: string;
selector: string;
html: string;
impact: "critical" | "serious" | "moderate" | "minor";
message: string;
context?: string;
element?: Element;
}
`

$3

Create a chunked audit that processes rules in time-boxed batches to avoid long tasks.

`js
const audit = createChunkedAudit(document);

function processNext() {
const hasMore = audit.processChunk(16); // 16ms budget per frame
if (hasMore) requestAnimationFrame(processNext);
else console.log(audit.getViolations());
}

processNext();
`

$3

Customize which rules are active.

`js
import { configureRules } from "@accesslint/core";

configureRules({
disabledRules: ["heading-order"],
});
`

$3

Array of all 84 bundled Rule objects.

$3

Returns bundled rules (minus disabled) plus any additional rules from configureRules().

$3

Look up a rule by its ID.

$3

Helpers for building custom rules:

- getAccessibleName(el) — compute the accessible name of an element
- getComputedRole(el) — get the computed ARIA role
- getImplicitRole(el) — get the implicit (native) ARIA role
- isAriaHidden(el) — check if an element is hidden via aria-hidden
- isValidRole(role) — check if a string is a valid ARIA role
- getAccessibleTextContent(el) — get text content respecting aria-hidden
- getSelector(el) — generate a CSS selector for an element
- getHtmlSnippet(el) — get a truncated HTML snippet of an element

Rules

84 rules covering WCAG 2.1 Level A and AA.

| Rule | Level | WCAG | Description |
| ---- | ----- | ---- | ----------- |
| document-title | A | 2.4.2 | Documents must have a