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Keep extension code quality predictable before issues reach runtime. ESLint runs outside the build pipeline. Run it from your scripts or continuous integration (CI).

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When ESLint is a good fit

  • You want consistent code standards across team contributions.
  • You need CI checks that catch common JS/TS mistakes early.
  • You are enforcing extension-specific quality rules before release.

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ESLint capabilities

CapabilityWhat it gives you
JavaScript and TypeScript lintingCatch common mistakes and enforce project standards
Flat config supportUse modern eslint.config.mjs in new projects
CI-friendly executionRun lint checks in local scripts and pull request pipelines
Extension-specific rulesetsAdd browser-extension plugins/rules when your team needs stricter checks

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Template examples

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ESLint configuration template

Preconfigured lint setup you can use immediately. new-config-eslint screenshot 
npx extension@latest create my-extension --template=new-config-eslint
Repository: examples/new-config-eslint

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Usage with an existing extension

Install the core packages: Create eslint.config.mjs: 
import globals from "globals";
import pluginJs from "@eslint/js";
import tseslint from "typescript-eslint";

export default [
  { files: ["**/*.{js,mjs,cjs,ts,tsx,jsx}"] },
  {
    languageOptions: {
      globals: globals.browser,
    },
  },
  pluginJs.configs.recommended,
  ...tseslint.configs.recommended,
];
Run lint commands from your scripts: 
npm run lint
If no script exists yet, run:

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Best practices

  • Keep lint rules in source control and apply them in CI.
  • Use lint-staged or pre-commit hooks for faster local feedback.
  • Add framework-specific plugins (for example, React) only when needed.

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Next steps

  • Integrate Prettier to avoid formatting-rule conflicts.
  • Add Stylelint for stylesheet linting.