Biome rules

Biome is the linter and formatter for JavaScript, JSX, and JSON in generated experiment projects. It replaces ESLint and Prettier.

Full configuration

The generated biome.json:

{
  "$schema": "https://biomejs.dev/schemas/2.5.0/schema.json",
  "files": {
    "includes": ["**", "!dist", "!scripts", "!lib"]
  },
  "formatter": {
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 120
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single"
    },
    "globals": [
      "window", "document", "fetch",
      "setTimeout", "setInterval", "clearInterval", "clearTimeout",
      "MutationObserver", "HTMLElement", "Intl", "s"
    ]
  },
  "assist": { "actions": { "source": { "organizeImports": "off" } } },
  "linter": {
    "enabled": true,
    "rules": {
      "preset": "none",
      "correctness": {
        "preset": "recommended",
        "noUndeclaredVariables": "error",
        "noUnusedVariables": "error"
      },
      "suspicious": {
        "preset": "recommended",
        "noConsole": "error"
      },
      "a11y": {
        "preset": "recommended"
      }
    }
  }
}

Formatter settings

Setting	Value	Reason
indentStyle	space	Uses spaces rather than tabs
indentWidth	2	Two-space indentation, matching generated source and config files
lineWidth	120	Leaves room for JSX without forcing frequent wraps
quoteStyle	single	Single quotes throughout

Import sorting

Generated projects leave Biome import sorting disabled with organizeImports: "off". Keep imports readable, but do not expect pnpm format to reorder them.

Linter rules

Recommended rule groups

The generated config keeps the top-level recommended setting off, then enables recommended rules in these groups:

Group	Why it is enabled
correctness	Catches likely runtime errors and unused variables.
suspicious	Catches code that is usually accidental, including console logging.
a11y	Catches common accessibility issues in JSX.

noConsole: error

// Fails the build
console.log('debug value:', data);

// Use the runtime's opt-in diagnostic helper instead
debug('product data', data);

console.log statements in IIFE bundles appear in all users' browser consoles. This rule prevents accidental logging in production bundles.

noUnusedVariables: error

// WRONG - unused import fails the build
import { waitFor, watchFor } from '@sogody/experiment-framework/framework';
// watchFor is never used

// CORRECT - only import what you use
import { waitFor } from '@sogody/experiment-framework/framework';

This rule catches imports and variables left behind during editing.

Globals

The javascript.globals array tells Biome which identifiers are available as browser globals without being imported:

Global	Source
window, document	Browser DOM
fetch	Browser Fetch API
setTimeout, setInterval, clearTimeout, clearInterval	Browser timer APIs
MutationObserver	Browser Observer API
HTMLElement	Browser DOM
Intl	Browser Internationalization API
s	Adobe Analytics AppMeasurement global

The s global is specific to the Samsung/Adobe Analytics setup. Biome will not flag s.tl() or s.events as undeclared.

Ignored paths

Path	Reason
dist/**	Build output - not source
node_modules/**	Dependencies
scripts/**	Build scripts run outside the experiment context
lib/**	Framework runtime - not linted per project

Commands

# Check for violations without writing files
pnpm lint

# Format and apply safe fixes
pnpm format

Common errors and fixes

Error	Cause	Fix
noConsole	console.log in src/	Remove it or use framework log() / debug()
noUnusedVariables	Unused import or declared variable	Remove the unused declaration
Formatting	Tabs instead of spaces, wrong quote style	Run pnpm format to auto-fix
Import order	Imports are hard to scan	Reorder imports manually when needed