Tree-Sitter JavaScript Parser

A simple Node.js application that fetches JavaScript/JSON files from URLs and parses them using Tree-Sitter to display the Abstract Syntax Tree (AST) in a readable format.

Features

• Fetch JavaScript/JSON files from any URL
• Parse code using Tree-Sitter JavaScript grammar
• Display AST in a hierarchical, indented format
• Built-in error handling
• Uses Node.js built-in fetch (no external dependencies except Tree-Sitter)

Prerequisites

• Node.js v18+ (for built-in fetch support)
• npm

Installation

1. Clone or download this repository
2. Install dependencies:

npm install tree-sitter tree-sitter-javascript

Usage

node index.js <URL>

Examples

Parse a JSON file:

node index.js https://raw.githubusercontent.com/facebook/react/main/packages/react/package.json

Parse a JavaScript file:

node index.js https://raw.githubusercontent.com/nodejs/node/main/lib/util.js

Sample Output

Parsing successful!
program: "{"name": "react","version": "18.3.1","descriptio..."
  expression_statement: "{"name": "react","version": "18.3.1","descriptio..."
    object: "{"name": "react","version": "18.3.1","descriptio..."
      pair: ""name": "react""
        string: ""name""
          string_fragment: "name"
        string: ""react""
          string_fragment: "react"
      pair: ""version": "18.3.1""
        string: ""version""
          string_fragment: "version"
        string: ""18.3.1""
          string_fragment: "18.3.1"

How It Works

1. Fetch: Downloads the source code from the provided URL
2. Parse: Uses Tree-Sitter to create an Abstract Syntax Tree
3. Display: Recursively prints the tree structure with proper indentation

Dependencies

• tree-sitter: Core Tree-Sitter parsing library
• tree-sitter-javascript: JavaScript language grammar for Tree-Sitter

Error Handling

The application handles:

• Invalid URLs (404 errors)
• Network connection issues
• Parsing errors
• Missing arguments

Notes

• Only displays the first 50 characters of each node's text content
• Uses 2-space indentation for each tree level
• Supports any publicly accessible URL that returns JavaScript or JSON content

License

MIT