ast-grep

Execute AST-based search, linting, and codemod rewrites with syntax-aware patterns.

1|1|Updated May 3, 2026

Search Tags:#typescript #ast-grep #lint #codemod #code-search #structural-editing

Ready to run

npx skills add https://github.com/matt-riley/agent-skills --skill ast-grep-matt-riley

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: ast-grep
Source: https://github.com/matt-riley/agent-skills/tree/main/skills/ast-grep
Command: npx skills add https://github.com/matt-riley/agent-skills --skill ast-grep-matt-riley

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) and references (resource) components.

What problem does it solve?

AST-based code search, linting, and codemod rewrites enable structure-aware edits over plain-text searches, reducing false positives and enabling scalable refactors.

Core Features & Use Cases

Structural search and pattern matching over code to identify API usage, anti-patterns, or refactor targets
Lint-rule style validations and safe codemod previews before applying changes
Use case: refactor a repetitive coding pattern across a large TS/JS codebase with confidence after previews

Quick Start

Execute an AST-based search or rewrite using the provided CLI with explicit language and scoped paths.

Frequently Asked Questions about ast-grep

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I refactor repetitive coding patterns across a large TypeScript codebase safely?▼

AST-based codemod rewrites refactor repetitive TypeScript patterns by applying syntax-aware transformations. You get safe previews before applying changes, ensuring reproducible results across large codebases without false positives from plain-text search.

What is structural code search and how does it reduce false positives?▼

Structural code search parses abstract syntax trees to match code patterns based on syntax and semantics rather than text. This structure-aware approach eliminates false positives that plague plain-text regex searches when finding API usage or anti-patterns.

Can I preview codemod changes before applying them to my project?▼

Yes, AST-based codemod rewrites provide safe previews before applying any changes. You validate lint-rule style transformations against your scoped paths and confirm the structural edits before committing the rewrites to your codebase.

Does ast-grep work for pattern-based migrations in JavaScript and TypeScript?▼

ast-grep executes AST-based search and codemod rewrites for JavaScript and TypeScript pattern-based migrations. It applies syntax-aware transformations to scoped paths, enabling scalable refactors across supported languages with reproducible results.

What's the best way to lint for anti-patterns using syntax-aware rules?▼

AST-based linting validates code against syntax-aware rules by parsing abstract syntax trees instead of plain text. This structure-aware mechanism identifies anti-patterns and API usage accurately, reducing false positives during large-scale codebase analysis.

When should I use structural editing instead of plain-text search and replace?▼

Use structural editing when plain-text search produces false positives or misses semantic matches. AST-based rewrites parse syntax trees to apply safe, reproducible transformations, making them essential for large-scale refactors and pattern-based migrations.