Migration Guide

v1 → v2

v2 replaces ESLint with Biome, drops support for Node 16/18, and locks pnpm to an exact version. If you have an existing experiment project from v1, follow these steps.

Breaking changes summary

Area	v1	v2
Linter	ESLint + Prettier	Biome (lint + format in one tool)
Node	16, 18, or 20	20 minimum, 24 recommended
pnpm	any version	10.30.1 (exact — enforced by packageManager field)
Console logs	Allowed	noConsole: error — build fails if console.* is present
watchFor()	Not available	Added in v2.0.0

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Step 1: Remove old tooling

Delete node_modules and any ESLint config files:

rm -rf node_modules
rm -f .eslintrc .eslintrc.js .eslintrc.cjs .eslintrc.json .eslintignore
rm -f .prettierrc .prettierrc.js .prettierignore

Step 2: Add Biome

Copy biome.json from a freshly scaffolded v2 project into your project root. A minimal starting config:

{
    "$schema": "https://biomejs.dev/schemas/1.9.4/schema.json",
    "organizeImports": { "enabled": true },
    "linter": {
        "enabled": true,
        "rules": {
            "recommended": true,
            "suspicious": {
                "noConsole": "error"
            }
        }
    },
    "formatter": {
        "enabled": true,
        "indentStyle": "space",
        "indentWidth": 4,
        "lineWidth": 120
    },
    "javascript": {
        "formatter": {
            "quoteStyle": "single"
        },
        "globals": ["s", "window", "document"]
    }
}

Step 3: Update package.json scripts

Replace ESLint commands with Biome equivalents:

Before (v1):

{
    "scripts": {
        "lint": "eslint src --fix",
        "format": "prettier --write src"
    }
}

After (v2):

{
    "scripts": {
        "lint": "biome check src",
        "lint:fix": "biome check --write src"
    }
}

Also add the packageManager field to lock pnpm:

{
    "packageManager": "pnpm@10.30.1"
}

Step 4: Switch Node version and reinstall

nvm install 24
nvm use 24
node --version   # v24.x.x
pnpm install

Step 5: Fix Biome violations

Run the linter and address any errors:

pnpm lint

Common v1 → v2 violations:

Violation	Fix
noConsole error	Remove or replace console.log with a comment or tracking call
Double quotes flagged	Biome enforces single quotes — run pnpm lint:fix to auto-fix
var declarations	Replace with const or let

Auto-fix most issues

Run pnpm lint:fix first. Biome can auto-fix the majority of formatting and many linting issues.

Step 6: Verify the build

pnpm build

All variations should compile to dist/. If the build fails due to a noConsole violation, the error output shows the exact file and line number.

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Changelog

See the full Changelog for a complete list of new features added in v2.