Take a nested Javascript object and flatten it, or unflatten an object with delimited keys.
$ npm install flatFlattens the object - it'll return an object one level deep, regardless of how nested the original object was:
import { flatten } from 'flat'
flatten({
key1: {
keyA: 'valueI'
},
key2: {
keyB: 'valueII'
},
key3: { a: { b: { c: 2 } } }
})
// {
// 'key1.keyA': 'valueI',
// 'key2.keyB': 'valueII',
// 'key3.a.b.c': 2
// }Flattening is reversible too, you can call unflatten on an object:
import { unflatten } from 'flat'
unflatten({
'three.levels.deep': 42,
'three.levels': {
nested: true
}
})
// {
// three: {
// levels: {
// deep: 42,
// nested: true
// }
// }
// }Use a custom delimiter for (un)flattening your objects, instead of ..
When enabled, both flat and unflatten will preserve arrays and their
contents. This is disabled by default.
import { flatten } from 'flat'
flatten({
this: [
{ contains: 'arrays' },
{ preserving: {
them: 'for you'
}}
]
}, {
safe: true
})
// {
// 'this': [
// { contains: 'arrays' },
// { preserving: {
// them: 'for you'
// }}
// ]
// }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' }
// }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.
Maximum number of nested objects to flatten.
import { flatten } from '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 } }
// }Transform each part of a flat key before and after flattening.
import { flatten, unflatten } from 'flat'
flatten({
key1: {
keyA: 'valueI'
},
key2: {
keyB: 'valueII'
},
key3: { a: { b: { c: 2 } } }
}, {
transformKey: function(key){
return '__' + key + '__';
}
})
// {
// '__key1__.__keyA__': 'valueI',
// '__key2__.__keyB__': 'valueII',
// '__key3__.__a__.__b__.__c__': 2
// }
unflatten({
'__key1__.__keyA__': 'valueI',
'__key2__.__keyB__': 'valueII',
'__key3__.__a__.__b__.__c__': 2
}, {
transformKey: function(key){
return key.substring(2, key.length - 2)
}
})
// {
// key1: {
// keyA: 'valueI'
// },
// key2: {
// keyB: 'valueII'
// },
// key3: { a: { b: { c: 2 } } }
// }flat is also available as a command line tool. You can run it with npx:
npx flat foo.jsonOr install the flat command globally:
npm i -g flat && flat foo.jsonAccepts a filename as an argument:
flat foo.jsonAlso accepts JSON on stdin:
cat foo.json | flat