| # JSON5 – JSON for Humans | |
| [][Build | |
| Status] [][Coverage | |
| Status] | |
| JSON5 is an extension to the popular [JSON] file format that aims to be | |
| easier to **write and maintain _by hand_ (e.g. for config files)**. | |
| It is _not intended_ to be used for machine-to-machine communication. | |
| (Keep using JSON or other file formats for that. 🙂) | |
| JSON5 was started in 2012, and as of 2022, now gets **[>65M downloads/week](https://www.npmjs.com/package/json5)**, | |
| ranks in the **[top 0.1%](https://gist.github.com/anvaka/8e8fa57c7ee1350e3491)** of the most depended-upon packages on npm, | |
| and has been adopted by major projects like | |
| **[Chromium](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/runtime_enabled_features.json5;drc=5de823b36e68fd99009a29281b17bc3a1d6b329c), | |
| [Next.js](https://github.com/vercel/next.js/blob/b88f20c90bf4659b8ad5cb2a27956005eac2c7e8/packages/next/lib/find-config.ts#L43-L46), | |
| [Babel](https://babeljs.io/docs/en/config-files#supported-file-extensions), | |
| [Retool](https://community.retool.com/t/i-am-attempting-to-append-several-text-fields-to-a-google-sheet-but-receiving-a-json5-invalid-character-error/7626), | |
| [WebStorm](https://www.jetbrains.com/help/webstorm/json.html), | |
| and [more](https://github.com/json5/json5/wiki/In-the-Wild)**. | |
| It's also natively supported on **[Apple platforms](https://developer.apple.com/documentation/foundation/jsondecoder/3766916-allowsjson5)** | |
| like **MacOS** and **iOS**. | |
| Formally, the **[JSON5 Data Interchange Format](https://spec.json5.org/)** is a superset of JSON | |
| (so valid JSON files will always be valid JSON5 files) | |
| that expands its syntax to include some productions from [ECMAScript 5.1] (ES5). | |
| It's also a strict _subset_ of ES5, so valid JSON5 files will always be valid ES5. | |
| This JavaScript library is a reference implementation for JSON5 parsing and serialization, | |
| and is directly used in many of the popular projects mentioned above | |
| (where e.g. extreme performance isn't necessary), | |
| but others have created [many other libraries](https://github.com/json5/json5/wiki/In-the-Wild) | |
| across many other platforms. | |
| [Build Status]: https://app.travis-ci.com/json5/json5 | |
| [Coverage Status]: https://coveralls.io/github/json5/json5 | |
| [JSON]: https://tools.ietf.org/html/rfc7159 | |
| [ECMAScript 5.1]: https://www.ecma-international.org/ecma-262/5.1/ | |
| ## Summary of Features | |
| The following ECMAScript 5.1 features, which are not supported in JSON, have | |
| been extended to JSON5. | |
| ### Objects | |
| - Object keys may be an ECMAScript 5.1 _[IdentifierName]_. | |
| - Objects may have a single trailing comma. | |
| ### Arrays | |
| - Arrays may have a single trailing comma. | |
| ### Strings | |
| - Strings may be single quoted. | |
| - Strings may span multiple lines by escaping new line characters. | |
| - Strings may include character escapes. | |
| ### Numbers | |
| - Numbers may be hexadecimal. | |
| - Numbers may have a leading or trailing decimal point. | |
| - Numbers may be [IEEE 754] positive infinity, negative infinity, and NaN. | |
| - Numbers may begin with an explicit plus sign. | |
| ### Comments | |
| - Single and multi-line comments are allowed. | |
| ### White Space | |
| - Additional white space characters are allowed. | |
| [IdentifierName]: https://www.ecma-international.org/ecma-262/5.1/#sec-7.6 | |
| [IEEE 754]: http://ieeexplore.ieee.org/servlet/opac?punumber=4610933 | |
| ## Example | |
| Kitchen-sink example: | |
| ```js | |
| { | |
| // comments | |
| unquoted: 'and you can quote me on that', | |
| singleQuotes: 'I can use "double quotes" here', | |
| lineBreaks: "Look, Mom! \ | |
| No \\n's!", | |
| hexadecimal: 0xdecaf, | |
| leadingDecimalPoint: .8675309, andTrailing: 8675309., | |
| positiveSign: +1, | |
| trailingComma: 'in objects', andIn: ['arrays',], | |
| "backwardsCompatible": "with JSON", | |
| } | |
| ``` | |
| A more real-world example is [this config file](https://github.com/chromium/chromium/blob/feb3c9f670515edf9a88f185301cbd7794ee3e52/third_party/blink/renderer/platform/runtime_enabled_features.json5) | |
| from the Chromium/Blink project. | |
| ## Specification | |
| For a detailed explanation of the JSON5 format, please read the [official | |
| specification](https://json5.github.io/json5-spec/). | |
| ## Installation and Usage | |
| ### Node.js | |
| ```sh | |
| npm install json5 | |
| ``` | |
| #### CommonJS | |
| ```js | |
| const JSON5 = require('json5') | |
| ``` | |
| #### Modules | |
| ```js | |
| import JSON5 from 'json5' | |
| ``` | |
| ### Browsers | |
| #### UMD | |
| ```html | |
| <!-- This will create a global `JSON5` variable. --> | |
| <script src="https://unpkg.com/json5@2/dist/index.min.js"></script> | |
| ``` | |
| #### Modules | |
| ```html | |
| <script type="module"> | |
| import JSON5 from 'https://unpkg.com/json5@2/dist/index.min.mjs' | |
| </script> | |
| ``` | |
| ## API | |
| The JSON5 API is compatible with the [JSON API]. | |
| [JSON API]: | |
| https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON | |
| ### JSON5.parse() | |
| Parses a JSON5 string, constructing the JavaScript value or object described by | |
| the string. An optional reviver function can be provided to perform a | |
| transformation on the resulting object before it is returned. | |
| #### Syntax | |
| JSON5.parse(text[, reviver]) | |
| #### Parameters | |
| - `text`: The string to parse as JSON5. | |
| - `reviver`: If a function, this prescribes how the value originally produced by | |
| parsing is transformed, before being returned. | |
| #### Return value | |
| The object corresponding to the given JSON5 text. | |
| ### JSON5.stringify() | |
| Converts a JavaScript value to a JSON5 string, optionally replacing values if a | |
| replacer function is specified, or optionally including only the specified | |
| properties if a replacer array is specified. | |
| #### Syntax | |
| JSON5.stringify(value[, replacer[, space]]) | |
| JSON5.stringify(value[, options]) | |
| #### Parameters | |
| - `value`: The value to convert to a JSON5 string. | |
| - `replacer`: A function that alters the behavior of the stringification | |
| process, or an array of String and Number objects that serve as a whitelist | |
| for selecting/filtering the properties of the value object to be included in | |
| the JSON5 string. If this value is null or not provided, all properties of the | |
| object are included in the resulting JSON5 string. | |
| - `space`: A String or Number object that's used to insert white space into the | |
| output JSON5 string for readability purposes. If this is a Number, it | |
| indicates the number of space characters to use as white space; this number is | |
| capped at 10 (if it is greater, the value is just 10). Values less than 1 | |
| indicate that no space should be used. If this is a String, the string (or the | |
| first 10 characters of the string, if it's longer than that) is used as white | |
| space. If this parameter is not provided (or is null), no white space is used. | |
| If white space is used, trailing commas will be used in objects and arrays. | |
| - `options`: An object with the following properties: | |
| - `replacer`: Same as the `replacer` parameter. | |
| - `space`: Same as the `space` parameter. | |
| - `quote`: A String representing the quote character to use when serializing | |
| strings. | |
| #### Return value | |
| A JSON5 string representing the value. | |
| ### Node.js `require()` JSON5 files | |
| When using Node.js, you can `require()` JSON5 files by adding the following | |
| statement. | |
| ```js | |
| require('json5/lib/register') | |
| ``` | |
| Then you can load a JSON5 file with a Node.js `require()` statement. For | |
| example: | |
| ```js | |
| const config = require('./config.json5') | |
| ``` | |
| ## CLI | |
| Since JSON is more widely used than JSON5, this package includes a CLI for | |
| converting JSON5 to JSON and for validating the syntax of JSON5 documents. | |
| ### Installation | |
| ```sh | |
| npm install --global json5 | |
| ``` | |
| ### Usage | |
| ```sh | |
| json5 [options] <file> | |
| ``` | |
| If `<file>` is not provided, then STDIN is used. | |
| #### Options: | |
| - `-s`, `--space`: The number of spaces to indent or `t` for tabs | |
| - `-o`, `--out-file [file]`: Output to the specified file, otherwise STDOUT | |
| - `-v`, `--validate`: Validate JSON5 but do not output JSON | |
| - `-V`, `--version`: Output the version number | |
| - `-h`, `--help`: Output usage information | |
| ## Contributing | |
| ### Development | |
| ```sh | |
| git clone https://github.com/json5/json5 | |
| cd json5 | |
| npm install | |
| ``` | |
| When contributing code, please write relevant tests and run `npm test` and `npm | |
| run lint` before submitting pull requests. Please use an editor that supports | |
| [EditorConfig](http://editorconfig.org/). | |
| ### Issues | |
| To report bugs or request features regarding the JSON5 **data format**, | |
| please submit an issue to the official | |
| **[_specification_ repository](https://github.com/json5/json5-spec)**. | |
| Note that we will never add any features that make JSON5 incompatible with ES5; | |
| that compatibility is a fundamental premise of JSON5. | |
| To report bugs or request features regarding this **JavaScript implementation** | |
| of JSON5, please submit an issue to **_this_ repository**. | |
| ### Security Vulnerabilities and Disclosures | |
| To report a security vulnerability, please follow the follow the guidelines | |
| described in our [security policy](./SECURITY.md). | |
| ## License | |
| MIT. See [LICENSE.md](./LICENSE.md) for details. | |
| ## Credits | |
| [Aseem Kishore](https://github.com/aseemk) founded this project. | |
| He wrote a [blog post](https://aseemk.substack.com/p/ignore-the-f-ing-haters-json5) | |
| about the journey and lessons learned 10 years in. | |
| [Michael Bolin](http://bolinfest.com/) independently arrived at and published | |
| some of these same ideas with awesome explanations and detail. Recommended | |
| reading: [Suggested Improvements to JSON](http://bolinfest.com/essays/json.html) | |
| [Douglas Crockford](http://www.crockford.com/) of course designed and built | |
| JSON, but his state machine diagrams on the [JSON website](http://json.org/), as | |
| cheesy as it may sound, gave us motivation and confidence that building a new | |
| parser to implement these ideas was within reach! The original | |
| implementation of JSON5 was also modeled directly off of Doug’s open-source | |
| [json_parse.js] parser. We’re grateful for that clean and well-documented | |
| code. | |
| [json_parse.js]: | |
| https://github.com/douglascrockford/JSON-js/blob/03157639c7a7cddd2e9f032537f346f1a87c0f6d/json_parse.js | |
| [Max Nanasy](https://github.com/MaxNanasy) has been an early and prolific | |
| supporter, contributing multiple patches and ideas. | |
| [Andrew Eisenberg](https://github.com/aeisenberg) contributed the original | |
| `stringify` method. | |
| [Jordan Tucker](https://github.com/jordanbtucker) has aligned JSON5 more closely | |
| with ES5, wrote the official JSON5 specification, completely rewrote the | |
| codebase from the ground up, and is actively maintaining this project. | |