Lint

Run linting and fix code quality issues in the codebase.

Target

$ARGUMENTS

Lint Strategy for Solo Developers

1. Run Linting Commands

# ESLint (JavaScript/TypeScript)
npm run lint
npx eslint . --fix

# TypeScript Compiler
npx tsc --noEmit

# Prettier (formatting)
npx prettier --write .

# All together
npm run lint && npx tsc --noEmit && npx prettier --write .

2. Common ESLint Issues

TypeScript Errors

• Missing type annotations
• any types used
• Unused variables
• Missing return types

React/Next.js Issues

• Missing keys in lists
• Unsafe useEffect dependencies
• Unescaped entities in JSX
• Missing alt text on images

Code Quality

• Unused imports
• Console.log statements
• Debugger statements
• TODO comments

Best Practices

• No var, use const/let
• Prefer const over let
• No nested ternaries
• Consistent return statements

3. Auto-Fix What You Can

Safe Auto-Fixes

# Fix formatting
prettier --write .

# Fix ESLint auto-fixable rules
eslint --fix .

# Fix import order
eslint --fix --rule 'import/order: error' .

Manual Fixes Needed

• Type annotations
• Logic errors
• Missing error handling
• Accessibility issues

4. Lint Configuration

ESLint Config (.eslintrc.json)

{
  "extends": [
    "next/core-web-vitals",
    "plugin:@typescript-eslint/recommended"
  ],
  "rules": {
    "@typescript-eslint/no-explicit-any": "error",
    "@typescript-eslint/no-unused-vars": "error",
    "no-console": "warn"
  }
}

Prettier Config (.prettierrc)

{
  "semi": false,
  "singleQuote": true,
  "tabWidth": 2,
  "trailingComma": "es5"
}

5. Priority Fixes

High Priority (fix immediately)

• Type errors blocking build
• Security vulnerabilities
• Runtime errors
• Broken accessibility

Medium Priority (fix before commit)

• Missing type annotations
• Unused variables
• Code style violations
• TODO comments

Low Priority (fix when convenient)

• Formatting inconsistencies
• Comment improvements
• Minor refactoring opportunities

6. Pre-Commit Hooks (Recommended)

Install Husky + lint-staged

npm install -D husky lint-staged
npx husky init

Configure (.husky/pre-commit)

npx lint-staged

lint-staged config (package.json)

{
  "lint-staged": {
    "*.{js,jsx,ts,tsx}": [
      "eslint --fix",
      "prettier --write"
    ]
  }
}

7. VSCode Integration

Settings (.vscode/settings.json)

{
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": true
  },
  "typescript.tsdk": "node_modules/typescript/lib"
}

What to Generate

1. Lint Report - All issues found
2. Auto-Fix Results - What was automatically fixed
3. Manual Fix Suggestions - Issues requiring manual intervention
4. Priority List - Ordered by severity
5. Configuration Recommendations - Improve lint setup

Common Fixes

Remove Unused Imports

// Before
import { A, B, C } from 'lib'

// After
import { A, C } from 'lib'  // B was unused

Add Type Annotations

// Before
function process(data) {
  return data.map(x => x.value)
}

// After
function process(data: DataItem[]): number[] {
  return data.map(x => x.value)
}

Fix Missing Keys

// Before
{items.map(item => <div>{item.name}</div>)}

// After
{items.map(item => <div key={item.id}>{item.name}</div>)}

Focus on fixes that improve code quality and prevent bugs. Run linting before every commit.