Show HN: Tree-hugger-JS: CSS selectors for JavaScript AST analysis and MCP https://ift.tt/K8eisHL

Show HN: Tree-hugger-JS: CSS selectors for JavaScript AST analysis and MCP I built a library that lets you find code patterns using familiar CSS-like selectors, then connected it to Claude via MCP so AI assistants can understand and refactor codebases. The Approach // Find code patterns with intuitive selectors: const asyncFunctions = tree.findAll('function[async]'); const todoComments = tree.findAll('comment[text ="TODO"]'); const reactHooks = tree.hooks(); // Built-in React support // Chain smart transformations: tree.transform() .rename('oldFunction', 'newFunction') .removeUnusedImports() .toString(); Key Features - CSS-like selectors: function[async], class:has(method), call[text*="fetch"] - Semantic aliases: function matches declarations, expressions, arrows, and methods - Smart transformations: Rename identifiers, remove unused imports, insert code - Built-in queries: functions, classes, imports, React hooks, JSX components - TypeScript support: Full parameter extraction with types - Scope analysis: Track variable bindings and references -- MCP -- I built an MCP server that exposes these capabilities to AI assistants. You can tell Claude: "Find all functions that use console.log and show me their parameters" And Claude can: 1. Parse your codebase 2. Use find_all_pattern('function:has(call[text ="console.log"])') 3. Extract parameter information with types 4. Give you detailed analysis Technical Details - Built on tree-sitter for correctness and performance - 13 MCP tools for comprehensive code analysis - Supports JavaScript, TypeScript, JSX, TSX - Pattern parser converts CSS selectors to AST predicates - Stateful MCP server maintains analysis context Links: - Library: https://ift.tt/BkDnYHL - MCP Server: https://ift.tt/4IRfVGu - NPM: npm install tree-hugger-js - Claude Code: claude mcp add tree-hugger-js-mcp npx tree-hugger-js-mcp Would love feedback from the community, especially on the MCP. June 21, 2025 at 03:11AM