A lightweight JSON library for Lua

Features

• Implemented in pure Lua: works with 5.1, 5.2, 5.3 and JIT
• Fast: generally outperforms other pure Lua JSON implementations (benchmark scripts)
• Tiny: around 290sloc, 9kb
• Proper error messages, eg: expected '}' or ',' at line 203 col 30

Usage

The json.lua file should be dropped into an existing project and required by it:

json = require "json"

The library provides the following functions:

json.encode(value)

Returns a string representing value encoded in JSON.

json.encode({ 1, 2, 3, { x = 10 } }) -- Returns '[1,2,3,{"x":10}]'

json.decode(str)

Returns a value representing the decoded JSON string.

json.decode('[1,2,3,{"x":10}]') -- Returns { 1, 2, 3, { x = 10 } }

Notes

• Trying to encode values which are unrepresentable in JSON will never result in type conversion or other magic: sparse arrays, tables with mixed key types or invalid numbers (NaN, -inf, inf) will raise an error
• null values contained within an array or object are converted to nil and are therefore lost upon decoding
• Alternatively null values may be encoded using json.null instead of nil
• Pretty encoding is not supported, json.encode() only encodes to a compact format

License

This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.