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Migrate from ESLint (and optionally Prettier) to Biome โ a fast, unified linter and formatter for JavaScript/TypeScript written in Rust. Migrates configuration, updates pre-commit hooks, and removes old dependencies.
When to Use This Skill
Use this skill when...
Keep ESLint when...
biome.json does not exist yet
You rely on an ESLint plugin with no Biome equivalent (e.g., eslint-plugin-react-hooks, eslint-plugin-jsx-a11y)
.eslintrc* or eslint.config.* exists
CI requires ESLint's exit codes specifically
You also want to replace Prettier with Biome formatter
Team has invested in custom ESLint rules
Using TypeScript and want a single tool
Important: Biome covers ~90% of common ESLint rules but not all plugins. Audit eslint-plugin-* dependencies before migrating. The most common unsupported plugins are accessibility (jsx-a11y) and framework hooks (react-hooks). You may need to keep ESLint alongside Biome for these.
Not covered by Biome โ keep ESLint for accessibility
eslint-plugin-react-hooks
Not covered by Biome โ keep ESLint for hooks rules
eslint-plugin-security
Partial coverage in Biome security/ rules
If unsupported plugins are found, ask the user whether to proceed with a partial migration (keep ESLint only for those plugins). If the user declines, abort.
Step 3: Create biome.json
Generate biome.json preserving equivalent rules from the existing ESLint and Prettier configurations:
Remove any ESLint/Prettier pre-commit hooks. Add Biome:
-repo:https://github.com/biomejs/pre-commitrev:v0.6.0# use latesthooks:-id:biome-checkadditional_dependencies: ["@biomejs/biome@1.9.0"]
Step 6: Delete old config files
Remove ESLint and Prettier config files (unless keeping ESLint for unsupported plugins โ in that case, keep .eslintrc but note Biome replaces most rules):
.eslintrc* โ delete (if full migration)
eslint.config.* โ delete (if full migration)
.prettierrc* โ delete
.eslintignore โ convert relevant patterns to biome.jsonignore section
Step 7: Verify migration
Run Biome to confirm it works:
npx @biomejs/biome check .
# or with bun:
bunx @biomejs/biome check .
Address any errors that weren't caught by ESLint (Biome may surface additional issues). Errors on first run are expected โ fix them or add to biome.json ignore rules.
Step 8: Report
Print a summary:
ESLint โ Biome migration complete
===================================
biome.json CREATED
package.json UPDATED (added @biomejs/biome, removed eslint/prettier)
.eslintrc.json DELETED / KEPT (partial migration)
.prettierrc DELETED
.pre-commit-config.yaml UPDATED (added biome-check hook)
Partial migration note (if applicable):
Kept eslint-plugin-jsx-a11y and eslint-plugin-react-hooks โ these plugins
have no Biome equivalent. ESLint is still needed for these rules.
Files to stage:
git add biome.json package.json .pre-commit-config.yaml
git add <deleted config files>
