Registry / serialization / yaml-ast-parser

yaml-ast-parser

library0.0.43jsnpmunverified

yaml-ast-parser is a JavaScript/TypeScript library designed to parse YAML documents into an Abstract Syntax Tree (AST). It is a fork of `js-yaml` but specifically focuses on providing AST representation rather than direct deserialization into JavaScript objects. Key features include the ability to restore parsing after errors, integrate error reporting directly into AST nodes, and built-in support for the `!include` tag commonly used in RAML specifications. The library is currently at version `0.0.43` and appears to be in an abandoned state, with the last GitHub activity several years ago. Its primary differentiator is the granular AST access and specialized `!include` handling, making it suitable for tools that need to analyze or transform YAML structure rather than just consume its data. Developers should be aware of its inactive maintenance status when considering its use in new projects.

serialization

npm install yaml-ast-parser

github ↗package ↗

INSTALL

IMPORT

SIG · YAML-AST-PARSER

yaml-ast-parser

serializationjavascriptv0.0.43

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

load

✓ import { load } from 'yaml-ast-parser';

✗ const { load } = require('yaml-ast-parser');

The `load` function is the primary entry point for parsing a YAML string into an AST. While CommonJS `require` might technically work in some environments due to transpilation, it's generally discouraged for type safety and modern module practices, especially since this library ships TypeScript types.

Kind

✓ import { Kind } from 'yaml-ast-parser';

✗ import { YAMLNodeKind } from 'yaml-ast-parser';

The `Kind` enum defines the types of YAML nodes (e.g., `SCALAR`, `MAP`, `SEQ`). It's crucial for type-checking and safely casting `YAMLNode` instances to their specific descendant types like `YAMLScalar` or `YamlMap`. Avoid adding `YAMLNode` prefix as it's just `Kind`.

YAMLNode

✓ import { YAMLNode, YAMLScalar, YamlMap, YAMLSequence, YAMLMapping } from 'yaml-ast-parser';

✗ import YAMLNode from 'yaml-ast-parser';

`YAMLNode` is the base interface for all AST nodes. To access specific properties like `value` on scalars or `mappings` on maps, you need to import and cast to the appropriate descendant type (e.g., `YAMLScalar`, `YamlMap`). It is not a default export.

determineScalarType

✓ import { determineScalarType, parseYamlBoolean, parseYamlFloat, parseYamlInteger } from 'yaml-ast-parser';

✗ import { determineType } from 'yaml-ast-parser';

These helper functions are used to inspect and parse the string `value` of a `YAMLScalar` based on the Core Schema rules. They are named exports and useful for interpreting scalar data.

This quickstart demonstrates how to parse a YAML string into an AST and then recursively traverse the resulting `YAMLNode` structure, printing the kind and value of each node. It highlights the use of `load`, `Kind` enum, and type casting for specific node types like `YAMLScalar`, `YamlMap`, and `YAMLSequence` to access their distinct properties.

import { load, Kind, YAMLScalar, YamlMap, YAMLSequence, YAMLMapping, YAMLNode } from 'yaml-ast-parser'; const yamlContent = ` name: John Doe age: 30 address: street: 123 Main St city: Anytown skills: - TypeScript - Node.js - YAML `; function traverseAST(node: YAMLNode, level: number = 0) { const indent = ' '.repeat(level); console.log(`${indent}Kind: ${Kind[node.kind]} (Pos: ${node.startPosition}-${node.endPosition})`); switch (node.kind) { case Kind.SCALAR: const scalarNode = node as YAMLScalar; console.log(`${indent} Value: '${scalarNode.value}'`); break; case Kind.MAP: const mapNode = node as YamlMap; mapNode.mappings.forEach(mapping => { console.log(`${indent} Key: '${(mapping.key as YAMLScalar).value}'`); traverseAST(mapping.value, level + 1); }); break; case Kind.SEQ: const sequenceNode = node as YAMLSequence; sequenceNode.items.forEach(item => { traverseAST(item, level + 1); }); break; case Kind.MAPPING: const mappingNode = node as YAMLMapping; // Key is a scalar, Value is a general YAMLNode console.log(`${indent} Mapping Key: '${(mappingNode.key as YAMLScalar).value}'`); traverseAST(mappingNode.value, level + 1); break; default: // Handle other kinds if necessary break; } } const ast = load(yamlContent); if (ast) { console.log('YAML AST Root Node:'); traverseAST(ast); } else { console.error('Failed to parse YAML content.'); }

Debug

Known issues

gotchaThe `yaml-ast-parser` project appears to be abandoned, with no significant updates or commits in several years. This means there's no ongoing maintenance, bug fixes, or security patches, which could pose risks for long-term projects.

fix

For new projects, consider actively maintained YAML parsing libraries or forks that provide similar AST capabilities. For existing projects, pin the exact version to mitigate unexpected behavior, and be aware of potential vulnerabilities or unaddressed issues.

affects: >=0.0.43

gotchaThe library uses `0.0.x` versioning, which typically indicates a pre-1.0.0 state where the API is not yet stable and breaking changes can occur without major version bumps. Although the project is abandoned now, this was a common risk during its active development.

fix

Always pin exact versions (`npm install yaml-ast-parser@0.0.43`) and thoroughly test any updates, even minor ones, if a newer version were to be released. This is less critical now due to abandonment but important to note historically.

affects: >=0.0.1

gotcha`yaml-ast-parser` is a fork of `js-yaml`. While it adds AST functionality and `!include` support, it may not keep pace with `js-yaml`'s updates, bug fixes, or new features. This could lead to diverging behavior or missing compatibility with newer YAML specifications.

fix

Understand the specific differences between `yaml-ast-parser` and `js-yaml` relevant to your use case. If you rely on the fork's unique features, ensure they meet your requirements, and be prepared for potential incompatibilities with standard YAML parsers for complex documents.

affects: All

Errors

Common errors & fixes

TypeError: (0 , yaml_ast_parser_1.load) is not a function

This error often occurs when attempting to use CommonJS `require` with a library primarily designed for ES Modules, or when trying to destructure a default export as a named export.

fix

Ensure you are using ES Module syntax: `import { load } from 'yaml-ast-parser';`. If using TypeScript, check your `tsconfig.json` for `module` and `moduleResolution` settings (e.g., `"module": "commonjs"` or `"esnext"`, `"moduleResolution": "node"` or `"bundler"`).

Property 'value' does not exist on type 'YAMLNode'.

The `value` property is specific to `YAMLScalar` nodes, but you are trying to access it on the generic `YAMLNode` type without proper type narrowing or casting.

fix

Before accessing specific properties, check the `kind` of the `YAMLNode` using the `Kind` enum and cast it to the appropriate specific type. For example: `if (node.kind === Kind.SCALAR) { const scalarNode = node as YAMLScalar; console.log(scalarNode.value); }`

Cannot read properties of undefined (reading 'items')

This typically happens when trying to access the `items` property, which belongs to `YAMLSequence` nodes, on a node that is not a sequence (e.g., a scalar or a map).

fix

Ensure that you verify the `kind` of the `YAMLNode` before attempting to access type-specific properties. For sequences: `if (node.kind === Kind.SEQ) { const sequenceNode = node as YAMLSequence; sequenceNode.items.forEach(...); }`

Upgrade

Version history

0.0.43latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

21 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/mulesoft-labs/yaml-ast-parser ↗

packagehttps://www.npmjs.com/package/yaml-ast-parser ↗