yamljs

What is yamljs?

The yamljs npm package is a library designed to parse YAML ('YAML Ain't Markup Language') strings and generate JavaScript objects, and vice versa. It provides an easy way to convert data between YAML, a human-friendly data serialization standard, and JavaScript objects. This can be particularly useful for configuration files, data exchange, and more, where YAML's readability and JavaScript's ubiquity are advantageous.

What are yamljs's main functionalities?

Parsing YAML to JavaScript Object

This feature allows you to convert a YAML string into a JavaScript object. It's particularly useful for reading configuration files or data represented in YAML format and using it within a JavaScript application.

const YAML = require('yamljs');
const yamlString = 'greeting: hello\nname: world';
const object = YAML.parse(yamlString);
console.log(object); // Output: { greeting: 'hello', name: 'world' }

Stringifying JavaScript Object to YAML

This feature enables the conversion of JavaScript objects into YAML strings. It's useful for creating configuration files or data exchange where YAML's human-readable format is preferred.

const YAML = require('yamljs');
const object = { greeting: 'hello', name: 'world' };
const yamlString = YAML.stringify(object, 4);
console.log(yamlString); // Output: 'greeting: hello\nname: world'

Other packages similar to yamljs

js-yaml

js-yaml is another popular YAML parsing and serialization library that offers similar functionalities to yamljs. It provides comprehensive YAML support, including the ability to customize schemas, which makes it more flexible in handling various YAML specifications compared to yamljs. js-yaml is known for its performance and extensive feature set.

yaml

The 'yaml' package is a modern YAML parser and stringifier, supporting YAML 1.2. It focuses on being highly compliant with the YAML specification and offers a simple API for parsing and stringifying. Compared to yamljs, it might offer better support for newer YAML features and specifications.

README

yaml.js

Standalone JavaScript YAML 1.2 Parser & Encoder. Works under node.js and all major browsers. Also brings command line YAML/JSON conversion tools.

Mainly inspired from Symfony Yaml Component.

How to use

Import yaml.js in your html page:

<script type="text/javascript" src="yaml.js"></script>

Parse yaml string:

nativeObject = YAML.parse(yamlString);

Dump native object into yaml string:

yamlString = YAML.stringify(nativeObject[, inline /* @integer depth to start using inline notation at */[, spaces /* @integer number of spaces to use for indentation */] ]);

Load yaml file:

nativeObject = YAML.load('file.yml');

Load yaml file:

YAML.load('file.yml', function(result)
{
    nativeObject = result;
});

Use with node.js

Install module:

npm install yamljs

Use it:

YAML = require('yamljs');

// parse YAML string
nativeObject = YAML.parse(yamlString);

// Generate YAML
yamlString = YAML.stringify(nativeObject, 4);

// Load yaml file using require
nativeObject = require('./myfile.yml');

// Load yaml file using YAML.load
nativeObject = YAML.load('myfile.yml');

Command line tools

You can enable the command line tools by installing yamljs as a global module:

npm install -g yamljs

Then, two cli commands should become available: yaml2json and json2yaml. They let you convert YAML to JSON and JSON to YAML very easily.

yaml2json

usage: yaml2json [-h] [-v] [-p] [-i INDENTATION] [-s] [-r] [-w] input

Positional arguments:
  input                 YAML file or directory containing YAML files.

Optional arguments:
  -h, --help            Show this help message and exit.
  -v, --version         Show program's version number and exit.
  -p, --pretty          Output pretty (indented) JSON.
  -i INDENTATION, --indentation INDENTATION
                        Number of space characters used to indent code (use 
                        with --pretty, default: 2).
  -s, --save            Save output inside JSON file(s) with the same name.
  -r, --recursive       If the input is a directory, also find YAML files in 
                        sub-directories recursively.
  -w, --watch           Watch for changes.

json2yaml

usage: json2yaml [-h] [-v] [-d DEPTH] [-i INDENTATION] [-s] [-r] [-w] input

Positional arguments:
  input                 JSON file or directory containing JSON files.

Optional arguments:
  -h, --help            Show this help message and exit.
  -v, --version         Show program's version number and exit.
  -d DEPTH, --depth DEPTH
                        Set minimum level of depth before generating inline 
                        YAML (default: 2).
  -i INDENTATION, --indentation INDENTATION
                        Number of space characters used to indent code 
                        (default: 2).
  -s, --save            Save output inside YML file(s) with the same name.
  -r, --recursive       If the input is a directory, also find JSON files in 
                        sub-directories recursively.
  -w, --watch           Watch for changes.

examples

# Convert YAML to JSON and output resulting JSON on the console
yaml2json myfile.yml

# Store output inside a JSON file
yaml2json myfile.yml > ouput.json

# Output "pretty" (indented) JSON
yaml2json myfile.yml --pretty

# Save the output inside a file called myfile.json
yaml2json myfile.yml --pretty --save

# Watch a full directory and convert any YAML file into its JSON equivalent
yaml2json mydirectory --pretty --save --recursive

# Convert JSON to YAML and store output inside a JSON file
json2yaml myfile.json > ouput.yml

# Output YAML that will be inlined only after 8 levels of indentation
json2yaml myfile.json --depth 8

# Save the output inside a file called myfile.json with 4 spaces for each indentation
json2yaml myfile.json --indentation 4

# Watch a full directory and convert any JSON file into its YAML equivalent
json2yaml mydirectory --pretty --save --recursive

Important

Symfony dropped support for YAML 1.1 spec. This means that yes, no and similar no longer convert to their boolean equivalents.

The internal Yaml().load() and Yaml().loadFile() methods renamed to Yaml().parse() and Yaml().parseFile() respectively. Exceptions replaced with YamlParseException object.