acorn

What is acorn?

Acorn is a fast, small, and standards-compliant JavaScript parser written in ECMAScript. It is used to parse JavaScript code and generate abstract syntax trees (ASTs), which can be analyzed or transformed by other tools. It is commonly used in the development of JavaScript compilers, static analysis tools, and code transformation utilities.

What are acorn's main functionalities?

Parsing JavaScript

This feature allows you to parse a string of JavaScript code into an abstract syntax tree (AST). The 'ecmaVersion' option specifies the ECMAScript version to parse.

const acorn = require('acorn');
const AST = acorn.parse('const x = 1;', { ecmaVersion: 2020 });

Walking the AST

This feature involves traversing the generated AST to visit different types of nodes. The 'acorn-walk' package provides utilities for walking the AST.

const acorn = require('acorn');
const walk = require('acorn-walk');
const AST = acorn.parse('const x = 1;', { ecmaVersion: 2020 });
walk.simple(AST, {
  Literal(node) {
    console.log(`Found a literal: ${node.value}`);
  }
});

Dynamic Import Parsing

This feature allows acorn to handle dynamic imports in the code. The 'acorn-dynamic-import' plugin extends acorn's capabilities to parse dynamic import() expressions.

const acorn = require('acorn');
const dynamicImport = require('acorn-dynamic-import').default;
const parser = acorn.Parser.extend(dynamicImport);
const AST = parser.parse('import("./module.js");', { ecmaVersion: 2020 });

Other packages similar to acorn

esprima

Esprima is a high performance, standard-compliant ECMAScript parser that also generates ASTs. It is similar to acorn in functionality but has a different API and extension mechanism.

cherow

Cherow is a JavaScript parser with a focus on performance and stability. It claims to be faster than acorn and esprima, and it supports a wide range of ECMAScript versions and experimental features.

README

Acorn

A tiny, fast JavaScript parser in JavaScript.

See http://marijnhaverbeke.nl/acorn/