code-antipatterns-analysis

# Code Anti-patterns Analysis

Expert knowledge for systematic detection and analysis of anti-patterns, code smells, and quality issues across codebases using ast-grep and parallel agent delegation.

## Analysis Philosophy

This skill emphasizes **parallel delegation** for comprehensive analysis. Rather than sequentially scanning for issues, launch multiple specialized agents to examine different categories simultaneously, then consolidate findings.

## Analysis Categories

### 1. JavaScript/TypeScript Anti-patterns

**Callback Hell & Async Issues**
```bash
# Nested callbacks (3+ levels)
ast-grep -p '$FUNC($$$, function($$$) { $FUNC2($$$, function($$$) { $$$ }) })' --lang js

# Missing error handling in async
ast-grep -p 'async function $NAME($$$) { $$$ }' --lang js
# Then check if try-catch is present

# Unhandled promise rejection
ast-grep -p '$PROMISE.then($$$)' --lang js
# Without .catch() - use composite rule
```

**Magic Values**
```bash
# Magic numbers in comparisons
ast-grep -p 'if ($VAR > 100)' --lang js
ast-grep -p 'if ($VAR < 50)' --lang js
ast-grep -p 'if ($VAR === 42)' --lang js

# Magic strings
ast-grep -p "if ($VAR === 'admin')" --lang js
```

**Empty Catch Blocks**
```bash
ast-grep -p 'try { $$$ } catch ($E) { }' --lang js
```

**Console Statements (Debug Leftovers)**
```bash
ast-grep -p 'console.log($$$)' --lang js
ast-grep -p 'console.debug($$$)' --lang js
ast-grep -p 'console.warn($$$)' --lang js
```

**var Instead of let/const**
```bash
ast-grep -p 'var $VAR = $$$' --lang js
```

### 2. Vue 3 Anti-patterns

**Props Mutation**
```yaml
# YAML rule for props mutation detection
id: vue-props-mutation
language: JavaScript
message: Avoid mutating props directly
rule:
  pattern: props.$PROP = $VALUE
```

```bash
# Direct prop assignment
ast-grep -p 'props.$PROP = $VALUE' --lang js
```

**Missing Keys in v-for**
```bash
# Search in Vue templates
ast-grep -p 'v-for="$ITEM in $LIST"' --lang html
# Check if :key is present nearby
```

**Options API in Compo