https://github.com/devlzl/runjs

JavaScript engine written in JavaScript.
https://github.com/devlzl/runjs

javascript-engine

Last synced: 7 days ago
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JavaScript engine written in JavaScript.

• Host: GitHub
• URL: https://github.com/devlzl/runjs
• Owner: devlzl
• Created: 2022-11-15T23:48:53.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2024-02-11T10:50:54.000Z (9 months ago)
• Last Synced: 2024-04-13T14:19:41.081Z (7 months ago)
• Topics: javascript-engine
• Language: JavaScript
• Homepage: https://devlzl.github.io/RunJS/
• Size: 12.7 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# RunJS JavaScript Engine

## 1. Introduction

RunJS is a small JavaScript engine written in JavaScript,  no external dependency.

It includes a set of classic JavaScript features in reference to the ECMA-262 Language Specification.

[Online Demo](https://devlzl.github.io/RunJS/)  

##  2. Usage

`main.js` provides a `run` function that accepts JavaScript source code as an argument.

You can import `run` anywhere and execute it.

## 3. Specifications

### 3.1 Language support

- Primitive data types and object

- Arithmetic and logical operations

- Conditional and iteration statements

- Function and scope

### 3.2 Standard library

```JavaScript

// Similar to console.log()

log(...args);

```

## 4. Internals

### 4.1 Lexer

Implemented lexical analysis using regular expressions.

### 4.2 Parser

Implemented syntax analysis from scratch according to LL algorithm, and construct AST.

### 4.3 Runtime

Implemented a set of runtime infrastructure:

- LanguageTypes

    - NumberType (represented as Float64Array)

    - StringType (represented as Uint16Array)

    - BooleanType

    - ObjectType

    - UndefinedType

    - NullType

- Realm

    - The `log` function is registered here

- SpecificationTypes

    - CompletionRecord

    - LexicalEnvironment

    - Reference

- ExecutionContext

### 4.4 Evaluator

When a new instance of the JavaScript engine is created, Realm will be created, ExecutionContextStack will be initialized, AST will be traversed and interpreted.