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Pretty-print your JSON in Ruby with more power than is provided by JSON.pretty_generate. Also includes a JavaScript version.
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NeatJSON

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Pretty-print your JSON in Ruby or JavaScript with more power than is provided by JSON.pretty_generate (Ruby) or JSON.stringify (JS). For example, like Ruby's pp (pretty print), NeatJSON can keep objects on one line if they fit, but break them over multiple lines if needed.

Features (all optional):

  • Keep values on one line, with variable wrap width.
  • Format numeric values to specified precision.
  • Sort object keys to be in alphabetical order.
  • Arbitrary whitespace (or really, any string) for indentation.
  • "Short" wrapping uses fewer lines, indentation based on values. (See last example below.)
  • Indent final closing bracket/brace for each array/object.
  • Adjust number of spaces inside array/object braces.
  • Adjust number of spaces before/after commas and colons (both for single- vs. multi-line).
  • Line up the values for an object across lines.
  • Online webpage for conversions and experimenting with options.

Table of Contents

Installation

  • Ruby: gem install neatjson
  • JavaScript (web): Clone the GitHub repo and copy javascript/neatjson.js
  • Node.js: npm install neatjson

Usage

Ruby:

require 'neatjson'
json = JSON.neat_generate( value, options )

JavaScript (web):

<script type="text/javascript" src="neatjson.js"></script>
<script type="text/javascript">
    var json = neatJSON( value, options );
</script>

Node.js:

const { neatJSON } = require('neatjson');
var json = neatJSON( value, options );

Examples

The following are all in Ruby, but similar options apply in JavaScript.

require 'neatjson'

o = { b:42.005, a:[42,17], longer:true, str:"yes\nplease" }

puts JSON.neat_generate(o)
#=> {"b":42.005,"a":[42,17],"longer":true,"str":"yes\nplease"}

puts JSON.neat_generate(o, sort:true)
#=> {"a":[42,17],"b":42.005,"longer":true,"str":"yes\nplease"}

puts JSON.neat_generate(o,sort:true,padding:1,after_comma:1)
#=> { "a":[ 42, 17 ], "b":42.005, "longer":true, "str":"yes\nplease" }

puts JSON.neat_generate(o, sort:true, wrap:40)
#=> {
#=>   "a":[42,17],
#=>   "b":42.005,
#=>   "longer":true,
#=>   "str":"yes\nplease"
#=> }

puts JSON.neat_generate(o, sort:true, wrap:40, decimals:2)
#=> {
#=>   "a":[42,17],
#=>   "b":42.01,
#=>   "longer":true,
#=>   "str":"yes\nplease"
#=> }

puts JSON.neat_generate(o, sort:->(k){ k.length }, wrap:40, aligned:true)
#=> {
#=>   "a"     :[42,17],
#=>   "b"     :42.005,
#=>   "str"   :"yes\nplease",
#=>   "longer":true
#=> }

puts JSON.neat_generate(o, sort:true, wrap:40, aligned:true, around_colon:1)
#=> {
#=>   "a"      : [42,17],
#=>   "b"      : 42.005,
#=>   "longer" : true,
#=>   "str"    : "yes\nplease"
#=> }

puts JSON.neat_generate(o, sort:true, wrap:40, aligned:true, around_colon:1, short:true)
#=> {"a"      : [42,17],
#=>  "b"      : 42.005,
#=>  "longer" : true,
#=>  "str"    : "yes\nplease"}

a = [1,2,[3,4,[5]]]
puts JSON.neat_generate(a)
#=> [1,2,[3,4,[5]]]

puts JSON.pretty_generate(a) # oof!
#=> [
#=>   1,
#=>   2,
#=>   [
#=>     3,
#=>     4,
#=>     [
#=>       5
#=>     ]
#=>   ]
#=> ]

puts JSON.neat_generate( a, wrap:true, short:true )
#=> [1,
#=>  2,
#=>  [3,
#=>   4,
#=>   [5]]]

data = ["foo","bar",{dogs:42,piggies:{color:'pink', tasty:true},
        barn:{jimmy:[1,2,3,4,5],jammy:3.141592653,hot:"pajammy"},cats:7}]

opts = { short:true, wrap:60, decimals:3, sort:true, aligned:true,
         padding:1, after_comma:1, around_colon_n:1 }

puts JSON.neat_generate( data, opts )
#=> [ "foo",
#=>   "bar",
#=>   { "barn"    : { "hot"   : "pajammy",
#=>                   "jammy" : 3.142,
#=>                   "jimmy" : [ 1, 2, 3, 4, 5 ] },
#=>     "cats"    : 7,
#=>     "dogs"    : 42,
#=>     "piggies" : { "color":"pink", "tasty":true } } ]

Options

You may pass any of the following options to neat_generate (Ruby) or neatJSON (JavaScript). Note: option names with underscores below use camelCase in JavaScript. For example:

# Ruby
json = JSON.neat_generate my_value, array_padding:1, after_comma:1, before_colon_n:2, indent_last:true
// JavaScript
var json = neatJSON( myValue, { arrayPadding:1, afterComma:1, beforeColonN:2, indentLast:true } );
  • wrap — Maximum line width before wrapping. Use false to never wrap, true to always wrap. default:80
  • indent — Whitespace used to indent each level when wrapping. default:" " (two spaces)
  • indent_last — Indent the closing bracket/brace for arrays and objects? default:false
  • short — Put opening brackets on the same line as the first value, closing brackets on the same line as the last? default:false
    • This causes the indent and indent_last options to be ignored, instead basing indentation on array and object padding.
  • sort — Sort objects' keys in alphabetical order (true), or supply a lambda for custom sorting. default:false
    • If you supply a lambda to the sort option, it will be passed three values: the (string) name of the key, the associated value, and the object being sorted, e.g. { sort:->(key,value,hash){ Float(value) rescue Float::MAX } }
  • aligned — When wrapping objects, line up the colons (per object)? default:false
  • decimals — Decimal precision for non-integer numbers; use false to keep values precise. default:false
  • array_padding — Number of spaces to put inside brackets for arrays. default:0
  • object_padding — Number of spaces to put inside braces for objects. default:0
  • padding — Shorthand to set both array_padding and object_padding. default:0
  • before_comma — Number of spaces to put before commas (for both arrays and objects). default:0
  • after_comma — Number of spaces to put after commas (for both arrays and objects). default:0
  • around_comma — Shorthand to set both before_comma and after_comma. default:0
  • before_colon_1 — Number of spaces before a colon when the object is on one line. default:0
  • after_colon_1 — Number of spaces after a colon when the object is on one line. default:0
  • before_colon_n — Number of spaces before a colon when the object is on multiple lines. default:0
  • after_colon_n — Number of spaces after a colon when the object is on multiple lines. default:0
  • before_colon — Shorthand to set both before_colon_1 and before_colon_n. default:0
  • after_colon — Shorthand to set both after_colon_1 and after_colon_n. default:0
  • around_colon — Shorthand to set both before_colon and after_colon. default:0

You may omit the 'value' and/or 'object' parameters in your sort lambda if desired. For example:

# Ruby sorting examples
obj = {e:3, a:2, c:3, b:2, d:1, f:3}

JSON.neat_generate obj, sort:true                              # sort by key name
#=> {"a":2,"b":2,"c":3,"d":1,"e":3,"f":3}

JSON.neat_generate obj, sort:->(k){ k }                        # sort by key name (long way)
#=> {"a":2,"b":2,"c":3,"d":1,"e":3,"f":3}

JSON.neat_generate obj, sort:->(k,v){ [-v,k] }                 # sort by descending value, then by ascending key
#=> {"c":3,"e":3,"f":3,"a":2,"b":2,"d":1}

JSON.neat_generate obj, sort:->(k,v,h){ h.values.count(v) }    # sort by count of keys with same value
#=> {"d":1,"a":2,"b":2,"e":3,"c":3,"f":3}
// JavaScript sorting examples
var obj = {e:3, a:2, c:3, b:2, d:1, f:3};

neatJSON( obj, {sort:true} );                                              // sort by key name
// {"a":2,"b":2,"c":3,"d":1,"e":3,"f":3}

neatJSON( obj, { sort:function(k){ return k }} );                          // sort by key name (long way)
// {"a":2,"b":2,"c":3,"d":1,"e":3,"f":3}

neatJSON( obj, { sort:function(k,v){ return -v }} );                       // sort by descending value
// {"e":3,"c":3,"f":3,"a":2,"b":2,"d":1}

var countByValue = {};
for (var k in obj) countByValue[obj[k]] = (countByValue[obj[k]]||0) + 1;
neatJSON( obj, { sort:function(k,v){ return countByValue[v] } } );         // sort by count of same value
// {"d":1,"a":2,"b":2,"e":3,"c":3,"f":3}

Note that the JavaScript version of NeatJSON does not provide a mechanism for cascading sort in the same manner as Ruby.

License & Contact

NeatJSON is copyright ©2015–2017 by Gavin Kistner and is released under the MIT License. See the LICENSE.txt file for more details.

For bugs or feature requests please open issues on GitHub. For other communication you can email the author directly.

TODO (aka Known Limitations)

  • Figure out the best way to play with custom objects that use to_json for their representation.
  • Detect circular references.
  • Possibly allow illegal JSON values like NaN or Infinity.
  • Possibly allow "JSON5" output (legal identifiers unquoted, etc.)

HISTORY

  • v0.8.4 — May 3, 2018

    • Fix issue #27: Default sorting fails with on objects with mixed keys [Ruby only]
      • Thanks Reid Beels
  • v0.8.3 — February 20, 2017

    • Fix issue #25: Sorting keys on multi-line object using function does not work without "short" [JS only]
      • Thanks Bernhard Weichel
  • v0.8.2 — December 16th, 2016

    • Fix issue #22: Sorting keys on multi-line object does not work without "short" [JS only]
    • Update online interface to support tabs as well as spaces.
    • Update online interface to use a textarea for the output (easier to select and copy).
    • Update online interface turn off spell checking for input and output.
  • v0.8.1 — April 22nd, 2016

    • Make NeatJSON work with Opal (by removing all in-place string mutations)
  • v0.8 — April 21st, 2016

    • Allow sort to take a lambda for customized sorting of object key/values.
  • v0.7.2 — April 14th, 2016

    • Fix JavaScript library to support objects without an Object constructor (e.g. location).
    • Online HTML converter accepts arbitrary JavaScript values as input in addition to JSON.
  • v0.7.1 — April 6th, 2016

    • Fix Ruby library to work around bug in Opal.
  • v0.7 — March 26th, 2016

    • Add indentLast/indent_last feature.
  • v0.6.2 — February 8th, 2016

    • Use memoization to avoid performance stalls when wrapping deeply-nested objects/arrays. Thanks @chroche
  • v0.6.1 — October 12th, 2015

    • Fix handling of nested empty objects and arrays. (Would cause a runtime error in many cases.)
      • This change causes empty arrays in a tight wrapping scenario to appear on a single line where they would previously take up three lines.
  • v0.6 — April 26th, 2015

    • Added before_colon_1 and before_colon_n to distinguish between single-line and multi-line objects.
  • v0.5 — April 19th, 2015

    • Do not format integers (or floats that equal their integer) using decimals option.
    • Make neatJSON() JavaScript available to Node.js as well as web browsers.
    • Add (Node-based) testing for the JavaScript version.
  • v0.4 — April 18th, 2015

    • Add JavaScript version with online runner.
  • v0.3.2 — April 16th, 2015

    • Force YARD to use Markdown for documentation.
  • v0.3.1 — April 16th, 2015

    • Remove some debugging code accidentally left in.
  • v0.3 — April 16th, 2015

    • Fix another bug with short:true and wrapping array values inside objects.
  • v0.2 — April 16th, 2015

    • Fix bug with short:true and wrapping values inside objects.
  • v0.1 — April 15th, 2015

    • Initial release.
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