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

• 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

npm install seafox --save-dev

Seafox generatesAST according toESTree AST format, and can be used to performsyntactic analysis (parsing) orlexical analysis (tokenization) of a JavaScript program, and withES2015 and later a JavaScript program can be eithera script or a module.

Theparse method exposed bySeafox takes an optionaloptions object which allows you to specify whether to parse inscript mode (the default) or inmodule mode.

This is the available options:

{// Allow parsing using Module as the goal symbolmodule?: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:

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

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

The callback function have 4 arguments.

Theloc option needs to be enabled forstart andend. Otherwise this values will be set toundefined

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