json5 vs parse-json
JSON Parsing and Serialization Comparison
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What's JSON Parsing and Serialization?

JSON parsing and serialization libraries in JavaScript provide tools to convert data between JSON (JavaScript Object Notation) format and JavaScript objects. These libraries handle the process of encoding (serializing) JavaScript objects into JSON strings for storage or transmission, and decoding (parsing) JSON strings back into JavaScript objects. They ensure that the conversion is done correctly, handling various data types, nested structures, and special characters. These libraries are essential for web applications, APIs, and any JavaScript environment where data exchange in JSON format is required. json5 is a library that extends JSON (JavaScript Object Notation) to allow for more human-friendly syntax, including comments, trailing commas, and unquoted keys. It is particularly useful for parsing and serializing JSON-like data that may not conform to strict JSON standards. parse-json is a lightweight and fast library focused on parsing JSON strings into JavaScript objects. It provides a simple and efficient way to handle JSON parsing, with error handling for invalid JSON input. It is designed for performance and minimalism, making it ideal for applications that require quick and reliable JSON parsing without the overhead of additional features.

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json5105,190,4396,902235 kB36-MIT
parse-json85,890,72836611 kB23 months agoMIT
Feature Comparison: json5 vs parse-json

JSON Standard Compliance

  • json5:

    json5 is not fully compliant with the JSON standard, as it allows for additional syntax features such as comments, trailing commas, and unquoted keys. This makes it more flexible for human editing but less suitable for strict JSON applications.

  • parse-json:

    parse-json is fully compliant with the JSON standard, ensuring that it only parses valid JSON strings. It does not allow for any non-standard features, making it reliable for applications that require strict JSON parsing.

Performance

  • json5:

    json5 is slower than standard JSON parsers due to the additional complexity of handling non-standard syntax. However, the performance impact is generally negligible for small to medium-sized data. The trade-off is worth it for the added flexibility in parsing human-friendly JSON-like data.

  • parse-json:

    parse-json is optimized for speed and efficiency, making it one of the fastest JSON parsing libraries available. It is designed to handle large JSON strings quickly, making it ideal for performance-sensitive applications.

Error Handling

  • json5:

    json5 provides error handling for invalid JSON5 syntax, but it may not be as strict as other parsers. It allows for more lenient parsing, which can be helpful when dealing with imperfect data but may lead to ambiguity in error reporting.

  • parse-json:

    parse-json throws a clear and descriptive error when it encounters invalid JSON input. It is designed to provide immediate feedback on parsing errors, making it easier for developers to identify and fix issues in the data.

Use Case

  • json5:

    json5 is ideal for use cases where configuration files need to be human-readable and editable, such as in development environments or tools that require user-defined settings. Its ability to handle comments and non-standard syntax makes it perfect for scenarios where clarity and flexibility are important.

  • parse-json:

    parse-json is best suited for applications that consume JSON data from APIs, databases, or other sources where the data is expected to be in strict JSON format. Its focus on performance and reliability makes it a great choice for backend services, data processing applications, and any scenario where accurate JSON parsing is critical.

Ease of Use: Code Examples

  • json5:

    Parsing JSON5 with json5

    import JSON5 from 'json5';

const json5String = `{
  // This is a comment
  key: 'value', // Trailing comma
  unquotedKey: 'another value'
}`;

const parsed = JSON5.parse(json5String);
console.log(parsed);

const json5Output = JSON5.stringify(parsed, null, 2);
console.log(json5Output);
  • parse-json:

    Parsing JSON with parse-json

    import parseJson from 'parse-json';

const jsonString = '{"key": "value", "number": 42}';

try {
  const parsed = parseJson(jsonString);
  console.log(parsed);
} catch (error) {
  console.error('Invalid JSON:', error);
}
How to Choose: json5 vs parse-json
  • json5:

    Choose json5 if you need to work with JSON data that includes comments, trailing commas, or other non-standard features. It is ideal for configuration files and scenarios where human readability and editability are important.

  • parse-json:

    Choose parse-json if you are looking for a fast and efficient solution for parsing standard JSON strings. It is best suited for applications that require strict adherence to JSON standards and prioritize performance.

Similar Npm Packages to json5

json5 is a JavaScript library that extends JSON (JavaScript Object Notation) to allow for a more human-friendly syntax. It enables developers to write JSON-like data structures with additional features such as comments, unquoted keys, and trailing commas. This makes it easier to read and write configuration files or data structures without the strict syntax rules of standard JSON. By using json5, developers can create more maintainable and understandable data representations, especially in scenarios where configuration files are frequently edited.

While json5 offers a flexible approach to data representation, there are alternatives that also aim to improve upon standard JSON. One notable alternative is hjson. Hjson is a user-friendly alternative to JSON that allows for a more relaxed syntax, making it easier to read and write. It supports features like comments, multi-line strings, and more intuitive formatting options. Hjson is particularly useful for configuration files and data interchange where human readability is a priority.

For a detailed comparison between json5 and hjson, you can visit: Comparing hjson vs json5.

Similar Npm Packages to parse-json

parse-json is a lightweight JavaScript library that provides a simple way to parse JSON strings into JavaScript objects. It is designed to handle errors gracefully, offering informative error messages when parsing fails. This makes it a useful tool for developers who need to work with JSON data and want to ensure robust error handling in their applications. While parse-json is effective for parsing JSON, there are several alternatives that offer different features and capabilities. Here are a few notable ones:

  • fast-json-parse is a high-performance JSON parser that focuses on speed and efficiency. It is designed to be faster than the native JSON.parse method, making it a great choice for applications that require rapid parsing of large JSON datasets. If performance is a critical factor in your application, fast-json-parse is worth considering due to its optimized parsing capabilities.

  • json-parse-even-better-errors is an enhanced version of the native JSON parser that provides more detailed error messages when parsing fails. This library aims to improve the developer experience by offering clearer insights into what went wrong during parsing. If you often encounter JSON parsing errors and need better debugging information, this library can be a valuable addition to your toolkit.

  • json-parse-helpfulerror is another library focused on providing helpful error messages for JSON parsing. It enhances the native JSON.parse function by wrapping it and adding more context to errors, making it easier to identify issues in the JSON data. If you prioritize informative error handling in your JSON parsing, this library is a solid choice.

  • json5 is a JSON extension that allows for a more flexible syntax, making it easier to work with JSON-like data. It supports comments, trailing commas, and other features that are not part of standard JSON. If you need to work with JSON data that requires additional flexibility or readability, json5 is a great alternative to consider.

To explore how parse-json compares with these alternatives, check out the comparison: Comparing fast-json-parse vs json-parse-even-better-errors vs json-parse-helpfulerror vs json5 vs parse-json.

README for json5

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, ranks in the top 0.1% of the most depended-upon packages on npm, and has been adopted by major projects like Chromium, Next.js, Babel, Retool, WebStorm, and more. It's also natively supported on Apple platforms like MacOS and iOS.

Formally, the JSON5 Data Interchange Format 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 across many other platforms.

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.

Example

Kitchen-sink example:

{
  // 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 from the Chromium/Blink project.

Specification

For a detailed explanation of the JSON5 format, please read the official specification.

Installation and Usage

Node.js

npm install json5

CommonJS

const JSON5 = require('json5')

Modules

import JSON5 from 'json5'

Browsers

UMD

<!-- This will create a global `JSON5` variable. -->
<script src="https://unpkg.com/json5@2/dist/index.min.js"></script>

Modules

<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.

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.

require('json5/lib/register')

Then you can load a JSON5 file with a Node.js require() statement. For example:

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

npm install --global json5

Usage

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

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.

Issues

To report bugs or request features regarding the JSON5 data format, please submit an issue to the official specification repository.

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.

License

MIT. See LICENSE.md for details.

Credits

Aseem Kishore founded this project. He wrote a blog post about the journey and lessons learned 10 years in.

Michael Bolin independently arrived at and published some of these same ideas with awesome explanations and detail. Recommended reading: Suggested Improvements to JSON

Douglas Crockford of course designed and built JSON, but his state machine diagrams on the JSON website, 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.

Max Nanasy has been an early and prolific supporter, contributing multiple patches and ideas.

Andrew Eisenberg contributed the original stringify method.

Jordan Tucker 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.

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