Runtime

The runtime option controls which global variables are available during linting. Picking the wrong runtime leads to false positives for globals that are not available in your actual execution environment.

eslint.config.mjs

import { defineConfig, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  runtime: Runtime.Node
})

Available Runtimes

Runtime	Enum	Use It When
Universal	Runtime.Universal	Full-stack projects, or when you are unsure — adds both Node.js and browser globals.
Browser	Runtime.Browser	Front-end-only code. Removes Node.js globals to prevent accidental server-side assumptions.
Node	Runtime.Node	Back-end-only code (APIs, CLIs, scripts). Removes browser globals.
Worker	Runtime.Worker	Generic service workers and edge runtimes — adds Fetch API and worker globals.
Cloudflare	Runtime.Cloudflare	Cloudflare Workers projects — adds worker globals plus Cloudflare-specific globals such as DurableObject and WebSocketPair.
Bun	Runtime.Bun	Bun runtime projects.
Deno	Runtime.Deno	Deno runtime projects.

Runtime Details

Runtime.Universal (default)

Adds both Node.js and browser globals. This is the default when no explicit runtime is set and auto-detection cannot determine a clear signal.

Use this when your project is truly full-stack and source files mix server and client code (for example a Remix app with API routes and React components in the same tree).

import { defineConfig, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  runtime: Runtime.Universal
})

Runtime.Browser

Adds browser globals: window, document, navigator, location, history, localStorage, fetch, XMLHttpRequest, CustomEvent, and the full DOM API surface.

Does not include Node.js-specific globals like process, Buffer, __dirname, or require.

import { defineConfig, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  frameworks: { vue: true },
  runtime: Runtime.Browser
})

[!TIP] Most framework presets (React, Vue, Svelte, Solid, Angular, Astro) automatically narrow to Browser runtime. You usually do not need to set this explicitly for UI projects.

Runtime.Node

Adds Node.js globals: process, Buffer, __dirname, __filename, require, module, exports, global, setTimeout, setInterval, setImmediate, and clearImmediate.

Does not include browser DOM globals.

import { defineConfig, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  frameworks: { nest: true },
  runtime: Runtime.Node
})

Use Runtime.Node for: Express / Fastify / Hono APIs, NestJS applications, CLI tools and scripts, and Node.js cron jobs.

Runtime.Worker

Adds service worker and Fetch API globals: self, fetch, Request, Response, Headers, URL, URLSearchParams, ReadableStream, WritableStream, TransformStream, caches, crypto, and CryptoKey.

Does not include window (workers have no DOM access) and does not include Node.js-specific globals.

import { defineConfig, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  frameworks: { hono: true },
  runtime: Runtime.Worker
})

Use Runtime.Worker for: generic edge functions, Next.js middleware, and browser service workers.

Runtime.Cloudflare

Adds service worker globals plus Cloudflare Workers-specific globals such as DurableObject, WebSocketPair, and caches.

import { defineConfig, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  runtime: Runtime.Cloudflare
})

Hono projects with wrangler, @cloudflare/workers-types, or @cloudflare/vitest-pool-workers are detected as Cloudflare automatically. Browser frameworks deployed with Wrangler stay browser-first unless you explicitly choose Runtime.Cloudflare.

Runtime.Bun

Adds Bun, Node, and browser-compatible globals. Detection looks for Bun runtime types or Bun runtime configuration.

Runtime.Deno

Adds Deno and browser-compatible globals. Detection looks for Deno config files or the Deno ESLint plugin.

Auto-Detection

When no runtime is set explicitly, auto-detection reads package.json and the project file tree for signals:

Signal	Detected Runtime
Presence of next, astro, vite, solid-js, svelte, vue	Browser
Presence of @nestjs/core	Node
Presence of Hono plus wrangler, @cloudflare/workers-types, or @cloudflare/vitest-pool-workers	Cloudflare
Presence of Cloudflare worker signals without a browser framework	Cloudflare
Presence of Bun runtime config/types	Bun
Presence of Deno config/plugin signals	Deno
No clear signal	Universal

Detection precedence (highest wins): Cloudflare > Bun/Deno > Worker > Node > Browser > Universal.

Use detection: { runtime: false } to disable runtime auto-detection and rely solely on your explicit runtime option.

Runtime in Monorepos

Use the projects option to assign different runtimes to different workspace packages:

import { defineConfig, Preset, Runtime } from '@santi020k/eslint-config-basic'

export default await defineConfig({
  preset: Preset.Monorepo,
  projects: {
    'apps/edge-api': { runtime: Runtime.Worker },
    'apps/web': { frameworks: { next: true }, runtime: Runtime.Browser },
    'packages/cli': { runtime: Runtime.Node },
    'packages/sdk': { runtime: Runtime.Universal }
  }
})

Related Pages

• Presets — preset defaults per runtime
• Monorepo — per-package runtime scoping
• Configuration — full option reference