Biome Rules

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

Full configuration

The generated biome.json:

{
    "$schema": "https://biomejs.dev/schemas/1.9.4/schema.json",
    "files": {
        "ignore": ["dist/**", "node_modules/**", "scripts/**", "lib/**"]
    },
    "formatter": {
        "indentStyle": "space",
        "indentWidth": 4,
        "lineWidth": 120
    },
    "javascript": {
        "formatter": {
            "quoteStyle": "single"
        },
        "globals": [
            "window", "document", "fetch",
            "setTimeout", "setInterval", "clearInterval", "clearTimeout",
            "MutationObserver", "HTMLElement", "Intl", "s"
        ]
    },
    "organizeImports": {
        "enabled": false
    },
    "linter": {
        "enabled": true,
        "rules": {
            "recommended": false,
            "correctness": {
                "recommended": true,
                "noUnusedVariables": "error"
            },
            "suspicious": {
                "recommended": true,
                "noConsole": "error"
            },
            "a11y": {
                "recommended": true
            }
        }
    }
}

Formatter settings

Setting	Value	Reason
indentStyle	space	Consistent with surrounding Samsung codebase
indentWidth	4	4-space indentation
lineWidth	120	Wider than the 80-char default to accommodate JSX
quoteStyle	single	Single quotes throughout

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

// WRONG - will fail the build
console.log('debug value:', data);

// CORRECT - use the runtime's opt-in diagnostic helper
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 'create-experiment/framework';
// watchFor is never used

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

Unused variables and imports increase bundle size unnecessarily. This rule enforces clean imports.

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 (read-only - used in CI and build gate)
pnpm lint

# Auto-fix formatting violations
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