jintr

Jinter

A tiny JavaScript interpreter written in TypeScript

Note: This project was originally developed for use in YouTube.js.

Table of Contents

• Installation
• Usage
• API
  • interpret()
  • visitor
  • scope
• License

Installation

npm install jintr

Usage

Execute some JavaScript code:

// const Jinter = require('jintr').default;
import { Jinter } from 'jintr';

const code = `
  function sayHiTo(person) {
    console.log('Hi ' + person + '!');
  }
  
  sayHiTo('mom');
`

const jinter = new Jinter(code);
jinter.interpret();

---

Inject your own functions and variables into the interpreter:

// ...

jinter.visitor.on('println', (node, visitor) => {
  if (node.type === 'CallExpression' && node.callee.type === 'MemberExpression') {
    const args = node.arguments.map((arg) => visitor.visitNode(arg));
    return console.log(...args);
  }
});

// Ex: str.toArray();
jinter.visitor.on('toArray', (node, visitor) => {
  if (node.type === 'CallExpression' && node.callee.type === 'MemberExpression') {
    const obj = visitor.visitNode(node.callee.object);
    return obj.split('');    
  }  
});

// Or you can just intercept access to specific nodes;
jinter.visitor.on('myFn', (node, visitor) => {
  console.info('MyFn node just got accessed:', node);
  return 'proceed'; // tells the interpreter to continue execution 
});

jinter.interpret();

For more examples see /test and /examples.

API

• Jinter(code: string)
  • interpret()
  • visitor
  • scope

interpret()

Interprets the code passed to the constructor.

visitor

The node visitor. This is responsible for walking the AST and executing the nodes.

scope

Represents the global scope of the program.

License

Distributed under the MIT License.

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Changelog

1.0.0 (2023-04-08)

⚠ BREAKING CHANGES

• convert to ESModule (#4)
• overhaul interpreter (#3)

Features

• add != op (97e17f9)
• add !== op (475fc89)
• add >>> op (7cfdfdf)
• add ^ op (faa1904)
• add in op (3f2d00d)
• add instanceof op (c11f440)
• add typeof op (5836fec)
• add support for IfStatement & WhileStatement (5179eee)
• BinaryExp: add support for bitwise AND (af01ce4)

Bug Fixes

• for-stmts: do not return if body type is ExpressionStatement (7e43562)
• short-circuiting not working correctly (8b610d1)

Code Refactoring

• convert to ESModule (#4) (50e40db)
• overhaul interpreter (#3) (3b5e56e)