nodejs

YAMLStar Node.js Bindings

Node.js bindings for YAMLStar - a pure YAML 1.2 loader implemented in Clojure.

Features

• YAML 1.2 Spec Compliance: 100% compliant with YAML 1.2 core schema
• Pure Implementation: No dependencies on js-yaml or other external parsers
• Fast Native Performance: Uses GraalVM native-image shared library
• Simple API: Load YAML documents with a single method call
• Multi-Document Support: Load multiple YAML documents from a single string

Installation

Prerequisites

First, build and install the shared library:

cd ../libyamlstar
make native
sudo make install PREFIX=/usr/local

Or install to user-local directory:

cd ../libyamlstar
make native
make install PREFIX=~/.local

Install Node.js Package

npm install @yaml/yamlstar

For development:

npm install

Quick Start

const YAMLStar = require('@yaml/yamlstar');

// Create a YAMLStar instance
const ys = new YAMLStar();

// Load a simple YAML string
const data = ys.load('key: value');
console.log(data);  // { key: 'value' }

// Clean up when done
ys.close();

Usage Examples

Basic Types

const YAMLStar = require('@yaml/yamlstar');
const ys = new YAMLStar();

// Strings
ys.load('hello');  // 'hello'

// Integers
ys.load('42');  // 42

// Floats
ys.load('3.14');  // 3.14

// Booleans
ys.load('true');   // true
ys.load('false');  // false

// Null
ys.load('null');  // null

Collections

// Mappings (objects)
const data = ys.load(`
name: Alice
age: 30
city: Seattle
`);
// { name: 'Alice', age: 30, city: 'Seattle' }

// Sequences (arrays)
const data = ys.load(`
- apple
- banana
- orange
`);
// ['apple', 'banana', 'orange']

// Flow style
const data = ys.load('[a, b, c]');
// ['a', 'b', 'c']

Nested Structures

const data = ys.load(`
person:
  name: Alice
  age: 30
  hobbies:
    - reading
    - coding
    - hiking
`);
// {
//   person: {
//     name: 'Alice',
//     age: 30,
//     hobbies: ['reading', 'coding', 'hiking']
//   }
// }

Multi-Document YAML

// Load all documents from a multi-document YAML string
const docs = ys.loadAll(`---
name: Document 1
---
name: Document 2
---
name: Document 3
`);
// [
//   { name: 'Document 1' },
//   { name: 'Document 2' },
//   { name: 'Document 3' }
// ]

Type Coercion

YAMLStar follows YAML 1.2 core schema type inference:

const data = ys.load(`
string: hello
integer: 42
float: 3.14
bool_true: true
bool_false: false
null_value: null
`);
// {
//   string: 'hello',
//   integer: 42,
//   float: 3.14,
//   bool_true: true,
//   bool_false: false,
//   null_value: null
// }

Error Handling

try {
  const data = ys.load('invalid: yaml: syntax');
} catch (error) {
  console.error('Error loading YAML:', error.message);
}

Version Information

// Get YAMLStar version
const version = ys.version();
console.log(`YAMLStar version: ${version}`);

Resource Cleanup

const ys = new YAMLStar();

// ... use ys ...

// Clean up GraalVM isolate when done
ys.close();

API Reference

YAMLStar Class

new YAMLStar()

Create a new YAMLStar instance. Each instance maintains its own GraalVM isolate.

const ys = new YAMLStar();

load(yamlInput)

Load a single YAML document.

Parameters:

• yamlInput (string): String containing YAML content

Returns:

• JavaScript value representing the YAML document (object, array, string, number, boolean, or null)

Throws:

• Error if the YAML is malformed

Example:

const data = ys.load('key: value');

loadAll(yamlInput)

Load all YAML documents from a multi-document string.

Parameters:

• yamlInput (string): String containing one or more YAML documents

Returns:

• Array of JavaScript values, one per YAML document

Throws:

• Error if the YAML is malformed

Example:

const docs = ys.loadAll('---\ndoc1\n---\ndoc2');

version()

Get the YAMLStar version string.

Returns:

• string: Version string

Example:

const version = ys.version();

close()

Tear down the GraalVM isolate and free resources. Should be called when done using the instance.

Example:

ys.close();

Development

Running Tests

# Run all tests
make test

# Or directly with node
node test/test.js

Building libyamlstar

If you need to rebuild the shared library:

cd ../libyamlstar
make clean
make native

Requirements

• Node.js: 18.0.0 or higher
• libyamlstar: Shared library (installed separately)
• System: Linux or macOS
• Dependencies: @makeomatic/ffi-napi, ref-napi

Library Search Path

The module searches for libyamlstar.so (or .dylib on macOS) in:

1. Development path (relative to module: ../../libyamlstar/lib/)
2. Directories in LD_LIBRARY_PATH environment variable
3. /usr/local/lib (default install location)
4. ~/.local/lib (user-local install location)

Comparison to js-yaml

Feature	YAMLStar	js-yaml
YAML Version	1.2	1.2
Implementation	Pure Clojure	JavaScript
Type Inference	YAML 1.2 core schema	YAML 1.2 + custom
Native Performance	Yes (GraalVM)	No
Dependencies	libyamlstar.so	None

License

MIT License - See License file

Credits

Created by Ingy döt Net, inventor of YAML.

YAMLStar is built on the YAML Reference Parser (pure Clojure implementation).

Links

• GitHub: https://github.com/yaml/yamlstar
• YAML Specification: https://yaml.org/spec/1.2/spec.html