https://github.com/KFlash/seafox

A blazing fast 100% spec compliant, self-hosted javascript parser written in Typescript
https://github.com/KFlash/seafox

acorn ecmascript es2020 estree javascript parser parsing tc39 typescript

Last synced: 8 days ago
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A blazing fast 100% spec compliant, self-hosted javascript parser written in Typescript

• Host: GitHub
• URL: https://github.com/KFlash/seafox
• Owner: KFlash
• License: isc
• Created: 2019-12-02T00:55:04.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2023-03-04T05:28:00.000Z (over 1 year ago)
• Last Synced: 2024-06-02T19:35:46.182Z (25 days ago)
• Topics: acorn, ecmascript, es2020, estree, javascript, parser, parsing, tc39, typescript
• Language: TypeScript
• Homepage:
• Size: 8.02 MB
• Stars: 480
• Watchers: 15
• Forks: 14
• Open Issues: 7
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

Lists

• awesome-stars - seafox - hosted javascript parser written in Typescript | KFlash | 450 | (TypeScript)
• awesome-github-star - seafox - hosted javascript parser written in Typescript | KFlash | 468 | (TypeScript)

README

        
Seafox


 A blazing fast 100% spec compliant, self-hosted javascript parser written in Typescript.







    

    

    

    

    



## Features

* Conforms to the standard ECMAScript® 2021 (ECMA-262 11th Edition) language specification

* Support for additional ECMAScript features for Web Browsers

* Optionally track syntactic node locations

* Emits an ESTree-compatible abstract syntax tree

* Lexical analysis

* No backtracking

* Low memory usage

* Insane performance both on desktop computers and handheld devices

* Twice as fast as other Javascript parsers

* Very well tested (~33 000 unit tests with full code coverage)

* Lightweight - ~84 KB minified

## Installation

```sh

npm install seafox --save-dev

```

## API

Seafox generates `AST` according to [ESTree AST format](https://github.com/estree/estree), and can be used to perform [syntactic analysis](https://en.wikipedia.org/wiki/Parsing) (parsing) or [lexical analysis](https://en.wikipedia.org/wiki/Lexical_analysis) (tokenization) of a JavaScript program, and with `ES2015` and later a JavaScript program can be either [a script or a module](https://tc39.github.io/ecma262/index.html#sec-ecmascript-language-scripts-and-modules).

The `parse` method exposed by `Seafox` takes an optional `options` object which allows you to specify whether to parse in [`script`](https://tc39.github.io/ecma262/#sec-parse-script) mode (the default) or in [`module`](https://tc39.github.io/ecma262/#sec-parsemodule) mode.

This is the available options:

```js

{

  // Allow parsing using Module as the goal symbol

  module?: boolean;

  // The flag to enable start and end offsets and line/column location information to each node

  loc: false;

  // Disable web compatibility

  disableWebCompat: false;

  // The flag to attach raw property to each literal and identifier node

  raw: false;

  // Enabled directives

  directives: false;

  // The flag to allow return in the global scope

  globalReturn: false;

  // The flag to enable implied strict mode

  impliedStrict: false;

// Enable non-standard parenthesized expression node

  preserveParens: false;

   // Allows token extraction. Accepts only a function

  onToken: function() {}

}

```

Example usage:

```ts

import { parseScript, parseModule, parse } from './seafox';

parseScript('({x: [y] = 0} = 1)');

parseModule('({x: [y] = 0} = 1)', { directives: true, raw: true });

parse('({x: [y] = 0} = 1)', { module: true });

parse('({x: [y] = 0} = 1)');

```

# Lexical analysis

Lexical analysis can only be done during parsing and accepts only a function type as the option

```ts

 parseScript('foo = bar', { onToken: () => {}});

```

The callback function have 4 arguments.

| Arguments   | Description |

| ----------- | ------------------------------------------------------------ |

| `token`     | The token to be extracted |

| `value`     | Value of the extracted token |

| `start`     | Start position of the extracted token |

| `end`       | End position of the extracted token |

The `loc` option needs to be enabled for `start` and `end`. Otherwise this values will be set to `undefined`

# Performance

Seafox is developed for performance and low memory usage, and the parser is about 2x - 4x faster than all other javascript parsers.