hjson

What is hjson?

Hjson is a user interface for JSON. It allows you to write JSON in a more human-friendly format, making it easier to read and edit. Hjson supports comments, multi-line strings, and other features that make JSON more readable and maintainable.

What are hjson's main functionalities?

Parsing Hjson to JSON

This feature allows you to parse Hjson formatted strings into standard JSON objects. The code sample demonstrates how to convert a Hjson string with comments into a JSON object.

const Hjson = require('hjson');
const hjsonData = `{
  // This is a comment
  key: "value"
}`;
const jsonData = Hjson.parse(hjsonData);
console.log(jsonData);

Stringifying JSON to Hjson

This feature allows you to convert JSON objects into Hjson formatted strings. The code sample shows how to stringify a JSON object into a Hjson string with all keys quoted.

const Hjson = require('hjson');
const jsonData = { key: "value" };
const hjsonData = Hjson.stringify(jsonData, { quotes: 'all' });
console.log(hjsonData);

Reading Hjson from a file

This feature allows you to read Hjson data from a file and parse it into a JSON object. The code sample demonstrates reading a Hjson file and converting its content to a JSON object.

const Hjson = require('hjson');
const fs = require('fs');
const hjsonData = fs.readFileSync('data.hjson', 'utf8');
const jsonData = Hjson.parse(hjsonData);
console.log(jsonData);

Writing Hjson to a file

This feature allows you to write Hjson formatted strings to a file. The code sample shows how to convert a JSON object to a Hjson string and write it to a file.

const Hjson = require('hjson');
const fs = require('fs');
const jsonData = { key: "value" };
const hjsonData = Hjson.stringify(jsonData, { quotes: 'all' });
fs.writeFileSync('data.hjson', hjsonData);
console.log('Hjson data written to file');

Other packages similar to hjson

json5

JSON5 is an extension of JSON that aims to make JSON more human-friendly. It allows comments, trailing commas, and more. Compared to Hjson, JSON5 is closer to standard JSON but still offers some of the readability improvements.

yaml

YAML is a human-readable data serialization standard that can be used in conjunction with all programming languages. It is more flexible and readable than JSON but can be more complex. YAML supports comments, multi-line strings, and more, similar to Hjson.

toml

TOML is a data serialization language designed to be a minimal configuration file format that's easy to read due to its simplicity. It supports comments and is more readable than JSON, similar to Hjson.

README

hjson-js

Hjson, the Human JSON. A configuration file format for humans. Relaxed syntax, fewer mistakes, more comments.

{
  # specify rate in requests/second (because comments are helpful!)
  rate: 1000

  // prefer c-style comments?
  /* feeling old fashioned? */

  # did you notice that rate doesn't need quotes?
  hey: look ma, no quotes for strings either!

  # best of all
  notice: []
  anything: ?

  # yes, commas are optional!
}

The JavaScript implementation of Hjson is based on JSON-js. For other platforms see hjson.org.

Install from npm

npm install hjson

Usage

var Hjson = require('hjson');

var obj = Hjson.parse(hjsonText);
var text2 = Hjson.stringify(obj);

To keep comments intact see API.

From the Commandline

Install with npm install hjson -g.

usage: hjson [OPTIONS] [INPUT]

  hjson can be used to convert JSON from/to Hjson.

  hjson will read the given JSON/Hjson input file or read from stdin.
  - default: will output as Hjson.
    - with -sl: will output the opening brace on the same line.
    - with -root: will output braces for the root object.
    - with -quote: will quote all strings.
  - with -j or -json: will output as formatted JSON.
  - with -c or -json=compact: will output as JSON.

Sample:

• run hjson test.json > test.hjson to convert to Hjson
• run hjson -j test.hjson > test.json to convert to JSON

API

The API is the same for the browser and node.js version.

Hjson.parse(text, options)

This method parses JSON or Hjson text to produce an object or array.

• text: the string to parse as JSON or Hjson
• options: object
  • keepWsc: boolean, keep white space and comments. This is useful if you want to edit an hjson file and save it while preserving comments (default false)

Hjson.stringify(value, options)

This method produces Hjson text from a JavaScript value.

• value: any JavaScript value, usually an object or array.
• options: object
  • keepWsc: boolean, keep white space. See parse.
  • bracesSameLine: boolean, makes braces appear on the same line as the key name. Default false.
  • emitRootBraces: boolean, show braces for the root object. Default true.
  • quotes: string, controls how strings are displayed.
    • "min": no quotes whenever possible (default)
    • "always": always use quotes
  • space: specifies the indentation of nested structures. If it is a number, it will specify the number of spaces to indent at each level. If it is a string (such as '\t' or ' '), it contains the characters used to indent at each level.
  • eol: specifies the EOL sequence (default is set by Hjson.setEndOfLine())

Hjson.endOfLine(), .setEndOfLine(eol)

Gets or sets the stringify EOL sequence ('\n' or '\r\n'). When running with node.js this defaults to os.EOL.

Hjson.rt { parse, stringify }

This is a shortcut to roundtrip your comments when reading and updating a config file. It is the same as specifying the keepWsc option for the parse and stringify functions.

require-hook

Require a config file directly.

require("hjson/lib/require-config");
var cfg=require("./config.hjson");

modify & keep comments

You can modify a Hjson file and keep the whitespace & comments intact (round trip). This is useful if an app updates its config file.

// parse, keep whitespace and comments
// (they are stored in a non enumerable __WSC__ member)
var data = Hjson.rt.parse(text);

// modify like you normally would
data.foo = "text";

// you can also edit comments by accessing __WSC__
var wsc = data.__WSC__;
// __WSC__ for objects contains { c: {}, o: [] }
// - c with the actual comment and
// - o (array) with the order of the members
wsc.c.hugo = "just another test";
wsc.o.splice(2, 0, "hugo");
data.hugo = "value";

data.arrayWithComments = [ "a" ];
// __WSC__ for arrays is just an array with the
// comments ([0] for the space before the elements)
data.arrayWithComments.__WSC__ = [ "before a", "after a" ];

// convert back to Hjson
console.log(Hjson.rt.stringify(data));

History

see history.md