Skip to content
🚂 Flatten/unflatten nested Javascript objects
Branch: master
Clone or download
Latest commit 32432dd Jul 2, 2018
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
test Add explicit test for sorted keys. Jul 25, 2017
.gitignore first commit Oct 5, 2012
.travis.yml
LICENSE Add BSD 3-Clause Jul 25, 2014
README.md feat: add command line interface Jun 20, 2018
cli.js
index.js Format code using standard. Jul 25, 2017
package.json Release 4.1.0 Jul 2, 2018

README.md

flat Build Status

Take a nested Javascript object and flatten it, or unflatten an object with delimited keys.

Installation

$ npm install flat

Methods

flatten(original, options)

Flattens the object - it'll return an object one level deep, regardless of how nested the original object was:

var flatten = require('flat')

flatten({
    key1: {
        keyA: 'valueI'
    },
    key2: {
        keyB: 'valueII'
    },
    key3: { a: { b: { c: 2 } } }
})

// {
//   'key1.keyA': 'valueI',
//   'key2.keyB': 'valueII',
//   'key3.a.b.c': 2
// }

unflatten(original, options)

Flattening is reversible too, you can call flatten.unflatten() on an object:

var unflatten = require('flat').unflatten

unflatten({
    'three.levels.deep': 42,
    'three.levels': {
        nested: true
    }
})

// {
//     three: {
//         levels: {
//             deep: 42,
//             nested: true
//         }
//     }
// }

Options

delimiter

Use a custom delimiter for (un)flattening your objects, instead of ..

safe

When enabled, both flat and unflatten will preserve arrays and their contents. This is disabled by default.

var flatten = require('flat')

flatten({
    this: [
        { contains: 'arrays' },
        { preserving: {
              them: 'for you'
        }}
    ]
}, {
    safe: true
})

// {
//     'this': [
//         { contains: 'arrays' },
//         { preserving: {
//             them: 'for you'
//         }}
//     ]
// }

object

When enabled, arrays will not be created automatically when calling unflatten, like so:

unflatten({
    'hello.you.0': 'ipsum',
    'hello.you.1': 'lorem',
    'hello.other.world': 'foo'
}, { object: true })

// hello: {
//     you: {
//         0: 'ipsum',
//         1: 'lorem',
//     },
//     other: { world: 'foo' }
// }

overwrite

When enabled, existing keys in the unflattened object may be overwritten if they cannot hold a newly encountered nested value:

unflatten({
    'TRAVIS': 'true',
    'TRAVIS_DIR': '/home/travis/build/kvz/environmental'
}, { overwrite: true })

// TRAVIS: {
//     DIR: '/home/travis/build/kvz/environmental'
// }

Without overwrite set to true, the TRAVIS key would already have been set to a string, thus could not accept the nested DIR element.

This only makes sense on ordered arrays, and since we're overwriting data, should be used with care.

maxDepth

Maximum number of nested objects to flatten.

var flatten = require('flat')

flatten({
    key1: {
        keyA: 'valueI'
    },
    key2: {
        keyB: 'valueII'
    },
    key3: { a: { b: { c: 2 } } }
}, { maxDepth: 2 })

// {
//   'key1.keyA': 'valueI',
//   'key2.keyB': 'valueII',
//   'key3.a': { b: { c: 2 } }
// }

Command Line Usage

flat is also available as a command line tool. You can run it with npx:

npx flat foo.json

Or install the flat command globally:

npm i -g flat && flat foo.json

Accepts a filename as an argument:

flat foo.json

Also accepts JSON on stdin:

cat foo.json | flat
You can’t perform that action at this time.