https://github.com/okunishinishi/node-compressed-json

JSON key compressor
https://github.com/okunishinishi/node-compressed-json

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JSON key compressor

• Host: GitHub
• URL: https://github.com/okunishinishi/node-compressed-json
• Owner: okunishinishi
• License: mit
• Created: 2019-07-22T09:05:29.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2023-01-04T05:02:35.000Z (about 2 years ago)
• Last Synced: 2024-11-13T23:23:25.481Z (3 months ago)
• Topics: json
• Language: JavaScript
• Size: 474 KB
• Stars: 37
• Watchers: 1
• Forks: 2
• Open Issues: 8
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# compressed-json

[bd_npm_shield_url]: http://img.shields.io/npm/v/install-if-needed.svg?style=flat

[bd_npm_url]: http://www.npmjs.org/package/compressed-json

[![npm Version][bd_npm_shield_url]][bd_npm_url]

String base JSON compressor

If you seriously want to reduce your data size, consider using [msgpack](https://msgpack.org/index.html).

Use compressed-json only if you cannot handle binary for some reason.

## Install

```bash

npm i compressed-json

```

## Usage

```js

'use strict'

const cjson = require('compressed-json')

// Convert json object

const compressed = cjson.compress({ /* Large json */ })

const restored = cjson.decompress(compressed)

// Convert json string

const compressedString = cjson.compress.toString({ /* Some large json */ })

const restoredFromString = cjson.decompress.fromString(compressedString)

```

## How It Works

compressed-json has two logics:

* [Key-Compression](#key-compression-logic)

* [String-Value-Pointing](#string-value-pointing-logic)

### Example compression

**example-src.json**

```json

{

  "description": "This is example json",

  "entities": [

    {

      "id": 100,

      "name": "Dog",

      "desc": "This is desc of dog",

      "tag": ["animal"]

    },

    {

      "id": 101,

      "name": "Cat",

      "desc": "This is desc of cat",

      "tag": ["animal"]

    }

  ],

  "notes": [

    "Unique string will be kept as is",

    "Duplicated string will be combined",

    "Duplicated string will be combined",

    "p: string start with 'p:' will be escaped "

  ]

}

```

**example-compressed.json**

```json

{

  "_": {

    "0": "This is example json",

    "1": [

      {

        "2": 100,

        "3": "Dog",

        "4": "This is desc of dog",

        "5": [

          "p:0"

        ]

      },

      {

        "2": 101,

        "3": "Cat",

        "4": "This is desc of cat",

        "5": [

          "p:0"

        ]

      }

    ],

    "6": [

      "Unique string will be kept as is",

      "p:1",

      "p:1",

      "e:p: string start with 'p:' will be escaped "

    ]

  },

  "K": [

    "description",

    "entities",

    "id",

    "name",

    "desc",

    "tag",

    "notes"

  ],

  "P": [

    "animal",

    "Duplicated string will be combined"

  ]

}

```

### Structure of compressed json

| Key | Description |

| --- | ----------- |

| `K` | Array of original keys. Object keys are replaced with index of `K` in the compressed json |

| `P` | Pointed string values. Values are replaced with index of `P` in the compressed json |

| `_` | Compressed payload. Keeps original structure, but keys and values may be replaced with pointers to `K` or `P` |



### Key-Compression logic

All object keys are replaced with index of array stored in `K` of compressed JSON.

The more same key appears in original json, the more better compression.



### String-Value-Pointing

String values appeared at least two will replaced with pointer string with contains index of array stored in `P` of compressed JSON.

The more same string value appears in original json, the more better compression.