Biome Lint & TypeScript Type-Check
Quick Reference
| Error | Fix |
|---|---|
noImplicitAnyLet | Add type: let x; → let x: Type; |
noUnusedVariables | Prefix _: const foo → const _foo |
noUnusedFunctionParameters | Rename in destructure: {param} → {param: _param} |
noEmptyPattern | Replace {} with _opts: object |
noUnreachable | Remove dead code or wrap in block comment |
noInvalidUseBeforeDeclaration | Move declaration before usage or extract to const |
TS2322 | Type assertion or filter: as Record<string, string> |
TS2345 | Non-null assertion or default: value! or value?? '' |
TS7030 | Add explicit return: return undefined; |
TS2339 | Type assertion to extend: as Type & {prop?: T} |
Workflow
Biome Lint
# 1. Auto-fix
pnpm biome lint ./src --write
# 2. Check remaining errors
pnpm biome lint ./src
# 3. Fix import type issues
npx -y @biomejs/biome lint --only=style/useImportType ./src --writeTypeScript Check
# Single package
pnpm tsgo -p tsconfig.json --skipLibCheck --maxNodeModuleJsDepth 0 --noEmit
# All packages
pnpm -r exec just typecheckPer-Package Rule Override
Create local biome.json to override rules:
{
"root": false,
"extends": "//",
"linter": {
"rules": {
"correctness": { "useHookAtTopLevel": "warn" },
"a11y": { "useButtonType": "warn" }
}
}
}biome-ignore Comments
// biome-ignore lint/suspicious/noSelfCompare: NaN check
return x !== x;
// biome-ignore lint/correctness/noConstructorReturn: proxy pattern
return new Proxy();Detailed Guides
- Biome fixes — Full fix examples for each Biome rule
- TypeScript fixes — TS errors, ES version issues, cross-package deps
- Breaking changes — Zod 4, vitest 4, react-router v7, etc.