Seafox

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

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Features

• Conforms to the standard ECMAScript® 2020 (ECMA-262 10th Edition) language specification
• Support for additional ECMAScript features for Web Browsers
• Optionally track syntactic node locations
• Emits an ESTree-compatible abstract syntax tree.
• No backtracking
• Low memory usage
• Very well tested (~32 000 unit tests with full code coverage)
• Lightweight - ~84 KB minified

Installation

npm install seafox --save-dev

API

Seafox generates AST according to ESTree AST format, and can be used to perform syntactic analysis (parsing) of a JavaScript program, and with ES2015 and later a JavaScript program can be either a script or a module.

The parse method exposed by Seafox takes an optional options object which allows you to specify whether to parse in script mode (the default) or in module mode.

This is the available options:

{
  // 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;
}

Example usage:

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)');