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HanSON - JSON for Humans

Please note (September '22): This project is quite old and I would suggest you check out JSON5 instead of this project.

In Short

  • HanSON is JSON with comments, multi-line strings and unquoted property names.
  • Comments use JavaScript syntax (//, /**/).
  • Supports backticks as quotes (``) for multi-line strings.
  • You can use either double-quotes ("") or single-quotes ('') for single-line strings.
  • Property names do not require quotes if they are valid JavaScript identifiers.
  • Commas after the last list element or property will be ignored.
  • Every JSON string is valid HanSON.
  • HanSON can easily be converted to real JSON.


JSON is a great and very simple data format, especially if you are working with JavaScript. Increasingly configuration files are written in JSON, and often it is used as a simpler alternative to XML. Unfortunately, when you are creating larger JSON files by hand, you will notice some shortcomings: you need to quote all strings, even object keys; you can not easily have strings with several lines; and you can not include comments.

HanSON is an extension of JSON that fixes those shortcomings with a few simple additions to the JSON spec:

  • quotes for strings are optional if they follow JavaScript identifier rules.
  • you can alternatively use backticks, as in ES6's template string literal, as quotes for strings. A backtick-quoted string may span several lines and you are not required to escape regular quote characters, only backticks. Backslashes still need to be escaped, and all other backslash-escape sequences work like in regular JSON.
  • for single-line strings, single quotes ('') are supported in addition to double quotes ("")
  • you can use JavaScript comments, both single line (//) and multi-line comments (/* */), in all places where JSON allows whitespace.
  • Commas after the last list element or object property will be ignored.

Example HanSON

  listName: "Sesame Street Monsters", // note that listName needs no quotes
  content: [
      name: "Cookie Monster",
      /* Note the template quotes and unescaped regular quotes in the next string */
      background: `Cookie Monster used to be a
monster that ate everything, especially cookies.
These days he is forced to eat "healthy" food.`
    }, {
      // You can single-quote strings too:
      name: 'Herry Monster',
      background: `Herry Monster is a furry blue monster with a purple nose.
He's mostly retired today.`
    },    // don't worry, the trailing comma will be ignored

Converting HanSON to JSON

hanson is a command-line converter that will convert HanSON files to JSON. It is a Node.js package that can be installed using npm:

npm install -g hanson

After installation, convert a single file like this:

hanson input.hson output.json

You can also convert multiple files using the -m options. It will automatically change the file extension to .json:

hanson -m input1.hson input2.hson input3.hson input4.hson input5.hson

Grunt Task to Convert HanSON to JSON

The Grunt plugin grunt-hanson-plugin can help you converting HanSON files to JSON. More about it in its own repository.

Webpack loader to Convert HanSON to JSON

The Webpack loader hson-loader can help you converting HanSON files to JSON. More about it in its own repository.

Reading HanSON in JavaScript

hanson.js is a simple library for Node.js that provides you with a HanSON object which works pretty much like the JSON object, with the only difference being that hanson.parse() will accept HanSON.

var hanson = require('hanson');
var obj = hanson.parse(hansonSrc);

hanson.stringify() will currently write regular JSON and just invokes JSON.stringify(), but future versions may pretty-print the output and use backtick quotes for multi-line strings instead of \n.

There's also a toJSON() function that can convert your HanSON source into JSON:

var hanson = require('hanson');
var json = hanson.toJSON(hansonSrc);

How Can HanSON Help Me?

  • If you have configuration or descriptor files (like package.json), you can write them as HanSON and convert them with the command line tool or the Grunt task.
  • Multi-line strings make it feasible to use JSON/HanSON for larger template systems, e.g. to generate static HTML pages. Just write a small script that accepts HanSON and uses your favorite JavaScript template engine to create HTML. Actually this is why I started HanSON - I wanted to replace my XSLT-based template system.
  • You can, of course, extend your application to accept HanSON files.

Function to Convert HanSON

Want to use HanSON in your program, without including any libraries? Use this function to convert HanSON to JSON. It returns a JSON string that can be read using JSON.parse().

function toJSON(input) {
		var UNESCAPE_MAP = { '\\"': '"', "\\`": "`", "\\'": "'" };
		var ML_ESCAPE_MAP = {'\n': '\\n', "\r": '\\r', "\t": '\\t', '"': '\\"'};
		function unescapeQuotes(r) { return UNESCAPE_MAP[r] || r; }

		return input.replace(/`(?:\\.|[^`])*`|'(?:\\.|[^'])*'|"(?:\\.|[^"])*"|\/\*[^]*?\*\/|\/\/.*\n?/g, // pass 1: remove comments
							 function(s) {
			if (s.charAt(0) == '/')
				return '';
				return s;
		.replace(/(?:true|false|null)(?=[^\w_$]|$)|([a-zA-Z_$][\w_$]*)|`((?:\\.|[^`])*)`|'((?:\\.|[^'])*)'|"(?:\\.|[^"])*"|(,)(?=\s*[}\]])/g, // pass 2: requote
							 function(s, identifier, multilineQuote, singleQuote, lonelyComma) {
			if (lonelyComma)
				return '';
			else if (identifier != null)
					return '"' + identifier + '"';
			else if (multilineQuote != null)
				return '"' + multilineQuote.replace(/\\./g, unescapeQuotes).replace(/[\n\r\t"]/g, function(r) { return ML_ESCAPE_MAP[r]; }) + '"';
			else if (singleQuote != null)
				return '"' + singleQuote.replace(/\\./g, unescapeQuotes).replace(/"/g, '\\"') + '"';
				return s;


  • August 14, 2013: First release (0.1.0)
  • August 15, 2013: Replaced triple-quotes with backticks (1.0.0, backward-incompatible change)
  • August 19, 2013: Added support for single-quotes (1.1.0)
  • June 14, 2016: Support for STDIN/STDOUT in command line. Improved tests. Thank you, Matt Carter (1.2.0)


All code and documentation has been dedicated to the public domain: