eslint-linter-browserify

10.2.1 verified Sat Apr 25 auth: no javascript

A browser-compatible build of ESLint that runs the Linter API client-side without Node.js. Version 10.2.1 mirrors ESLint's core linting engine, made available for browser environments via bundlers like webpack or direct script tags. It ships TypeScript definitions and supports ESM, CJS, and UMD. Unlike server-side ESLint, only the Linter class is available (no CLI, no built-in formatters). Key differentiator: enables real-time linting in browser-based code editors such as CodeMirror or Monaco.

Common errors

error Cannot find module 'eslint-linter-browserify' ↓

cause Package not installed or not in node_modules.

fix

Run 'npm install eslint-linter-browserify' and ensure import path is correct.

error linter.verify is not a function ↓

cause Using default import instead of named import: 'import Linter from ...' returns the module object, not the Linter class.

fix

Use 'import { Linter } from 'eslint-linter-browserify''.

error ReferenceError: require is not defined ↓

cause Using CJS require in an ESM context (e.g., modern browser or Node with 'type':'module').

fix

Use import instead, or switch to a bundler that supports require.

error Failed to load rule 'no-undef': Cannot find module 'eslint/lib/rules/no-undef' ↓

cause Trying to load a rule that expects Node.js module resolution; browser build may not include all rules.

fix

Only use rules that are bundled with the linter. Check the package's bundled rules list.

Warnings

binding Only the Linter class is available; other ESLint APIs (CLIEngine, RuleTester, etc.) are not bundled. ↓

fix Use only Linter. For other APIs, consider server-side ESLint.

gotcha Rules that require file system access (e.g., 'import', 'node') may not work or behave differently in the browser. ↓

fix Only use syntax and built-in rules that don't rely on Node.js APIs. Test thoroughly.

deprecated The namespace import via <script> tag returns the linter object as window.eslint. Ensure script order if using multiple bundles. ↓

fix Use <script src='linter.js'> before any code that depends on window.eslint.

Install

npm install eslint-linter-browserify

yarn add eslint-linter-browserify

pnpm add eslint-linter-browserify

Imports

Linter

wrong

import Linter from 'eslint-linter-browserify'

correct

import { Linter } from 'eslint-linter-browserify'

Use named import, not default. The package exports an object with Linter property.

eslint (namespace)
wrong
```
const eslint = require('eslint-linter-browserify')
```
correct
```
import * as eslint from 'eslint-linter-browserify'
```
Both ESM and CJS work. For browser scripts, use UMD: <script src='...linter.js'> and access window.eslint.

type Linter

wrong

import { Linter } from 'eslint-linter-browserify' // no runtime import needed

correct

import type { Linter } from 'eslint-linter-browserify'

Only use type import when you only need the type, e.g. for TypeScript declarations.

Quickstart

Shows how to create a Linter instance, define rules, and verify code. Output is an array of lint messages.

import { Linter } from 'eslint-linter-browserify';

const linter = new Linter();
const code = "var foo = 1;";
const config = {
  rules: {
    semi: ["error", "always"],
    "no-var": ["error"]
  }
};
const messages = linter.verify(code, config, { filename: "test.js" });
console.log(messages);
// Example output: [{ line: 1, column: 1, message: "Unexpected var, use let or const instead.", ruleId: "no-var", severity: 2 }]