Astring

A tiny and fast JavaScript code generator from an ESTree-formatted AST.

Key features:

• Supports ECMAScript versions 5 and 6.
• Considerably faster than Escodegen.
• Smaller than Esotope and faster for small ASTs.
• No dependencies and small footprint (12 KB minified, 3 KB gziped).
• Output code is readable and executable.
• Reduced formatting options.

Installation

If you haven't already, install the Node Package Manager.

The easiest way is to install it with the Node Package Manager:

npm install astring

Alternatively, checkout this repository and install the development dependencies:

git clone https://github.com/davidbonnet/astring.git
cd astring
npm install

Usage

The path to the module file is dist/astring.min.js and works both in a browser or Node environment. When run in a browser, it creates a global variable astring.

The astring module consists of a function that takes two arguments: node and options. It returns a string representing the rendered code of the provided AST node. The options are:

• indent: string to use for indentation (defaults to \t)
• lineEnd: string to use for line endings (defaults to \n)
• startingIndentLevel: indent level to start from (defaults to 0)

Example

This example uses Acorn, a blazingly fast JavaScript parser and AST producer. It is the perfect companion of Astring.

// Import modules (unecessary when run in a browser)
acorn = require( 'acorn' );
astring = require( 'astring' );

// Example code
var code = "let answer = 4 + 7 * 5 + 3;\n";

// Parse it into an AST
var ast = acorn.parse( code, { ecmaVersion: 6 } );

// Set formatting options
var options = {
    indent: '   ',
    lineEnd: '\n'
};

// Format it
var result = astring( ast, options );

// Check it
if ( code === result ) {
    console.log( 'It works !' );
} else {
    console.log( 'Something went wrong…' );
}

TODO

• CLI
• Comments generation
• More tests