@teamteanpm2024/provident-expedita-recusandae
v1.0.5
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Walk objects like this guy.
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@teamteanpm2024/provident-expedita-recusandae
Walk objects like this guy.
Map over an object in a preorder or postoder depth-first manner. Also, provides functions for serializing and deserializng self-referential objects using JSON pointer.
This library is designed to work well with functions that traverse
an object in the same way JSON.stringify
and JSON.parse
do. Namely,
preorder and postorder. To mimic that behavior entirely set the jsonCompat
option to true
.
Custom traversal functions are supported for some functions. This allows you
to walk tree-like structures, such as a JSON schema, in a more efficient and
logical way. Prefer walkEach
in these scenarios.
map
, walkEach
, walkEachAsync
, mapLeaves
, compact
, and truncate
support
the option modifyInPlace
for in-place modification. Otherwise, the object is deep cloned.
export interface MutationOption {
/** Set to true to modify the object instead of returning a new object. */
modifyInPlace?: boolean
}
walker
walker(obj: object, walkFn: WalkFn, options: Options = {}) => void
Generic walking fn that traverses an object in preorder (default) or postorder,
calling walkFn
for each node. Can be used directly, but probably shouldn't.
export interface Node {
key: string | undefined
val: any
parents: any[]
path: string[]
isLeaf: boolean
isRoot: boolean
}
export interface Options {
postOrder?: boolean
jsonCompat?: boolean
traverse?(x: any): any
}
import { walker } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
a: {
b: 23,
c: 24,
},
d: {
e: 'Bob',
f: [10, 20, 30],
},
}
const nodes: Node[] = []
const walkFn = (node: Node) => {
nodes.push(node)
}
walker(obj, walkFn, options)
nodes
Returns an array of nodes. Note this is how walk
works, so prefer
that fn.
[
{
key: undefined,
parents: [],
val: { a: { b: 23, c: 24 }, d: { e: 'Bob', f: [10, 20, 30] } },
path: [],
isRoot: true,
isLeaf: false,
},
{
key: 'a',
val: { b: 23, c: 24 },
parents: [{ a: { b: 23, c: 24 }, d: { e: 'Bob', f: [10, 20, 30] } }],
path: ['a'],
isLeaf: false,
isRoot: false,
},
{
key: 'b',
val: 23,
parents: [
{ b: 23, c: 24 },
{ a: { b: 23, c: 24 }, d: { e: 'Bob', f: [10, 20, 30] } },
],
path: ['a', 'b'],
isLeaf: true,
isRoot: false,
},
...
]
walk
walk(obj: object, options: WalkOptions = {}) => Node[]
Walk an object. Returns an array of all nodes in the object in either preorder or postorder.
export interface WalkOptions extends Options {
leavesOnly?: boolean
}
import { walk } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
a: {
b: 23,
c: 24,
},
d: {
e: 'Bob',
f: [10, 20, 30],
},
}
walk(obj).map((x) => x.path)
Produces:
[
[],
["a"],
["a", "b"],
["a", "c"],
["d"],
["d", "e"],
["d", "f"],
["d", "f", "0"],
["d", "f", "1"],
["d", "f", "2"]
]
walkEach
walkEach(obj: object, walkFn: WalkFn, options: options?: WalkOptions & MutationOption) => object
export type WalkFn = (node: Node) => void
Walk over an object calling walkFn
for each node. The original
object is deep-cloned by default making it possible to simply mutate each
node as needed in order to transform the object. The cloned object
is returned if options.modifyInPlace
is not set to true.
Below I want to walk a MongoDB JSON schema and set additionalProperties
to true
wherever it exists. I traverse this tree using a custom traverse
fn.
The original object is not modified.
import { walkEach } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
bsonType: 'object',
additionalProperties: false,
required: ['name'],
properties: {
_id: {
bsonType: 'objectId',
},
name: { bsonType: 'string' },
addresses: {
bsonType: 'array',
items: {
bsonType: 'object',
additionalProperties: false,
properties: {
address: {
bsonType: 'object',
additionalProperties: false,
properties: {
zip: { bsonType: 'string' },
country: { bsonType: 'string' },
},
},
},
},
},
},
}
const traverse = (x: any) => x.properties || (x.items && { items: x.items })
const walkFn = ({ val }: Node) => {
if ('additionalProperties' in val) {
val.additionalProperties = true
}
}
walkEach(obj, walkFn, { traverse })
Produces:
{
bsonType: 'object',
additionalProperties: true,
required: ['name'],
properties: {
_id: { bsonType: 'objectId' },
name: { bsonType: 'string' },
addresses: {
bsonType: 'array',
items: {
bsonType: 'object',
additionalProperties: true,
properties: {
address: {
bsonType: 'object',
additionalProperties: true,
properties: {
zip: { bsonType: 'string' },
country: { bsonType: 'string' },
},
},
},
},
},
},
}
walkEachAsync
Like walkEach
but awaits the promise returned by walkFn
before proceeding to
the next node.
map
Map over an object modifying values with a fn depth-first in a preorder or postorder manner. The output of the mapper fn will be traversed if possible when traversing preorder.
By default, nodes will be excluded by returning undefined
.
Undefined array values will not be excluded. To customize
pass a fn for options.shouldSkip
.
map(obj: object, mapper: Mapper, options?: MapOptions & MutationOption) => object
export type Mapper = (node: Node) => any
export type MapOptions = Omit<Options, 'traverse'> & {
shouldSkip?(val: any, node: Node): boolean
}
import { map } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
a: {
b: 23,
c: 24,
},
d: {
e: 'Bob',
f: [10, null, 30, [31, undefined, 32], 40],
},
g: [25, '', { h: [null, 26, 27] }],
i: 'Frank',
}
map(obj, ({ val }) => (Array.isArray(val) ? _.compact(val) : val))
Produces:
{
a: { b: 23, c: 24 },
d: { e: 'Bob', f: [10, 30, [31, 32], 40] },
g: [25, { h: [26, 27] }],
i: 'Frank',
}
Postorder
const obj = {
bob: {
scores: ['87', 'x97', 95, false],
},
joe: {
scores: [92, 92.5, '73.2', ''],
},
frank: {
scores: ['abc', ''],
},
}
const result = map(
obj,
({ val, isLeaf }) => {
if (isLeaf) {
return parseFloat(val)
}
return Array.isArray(val) ? _.compact(val) : val
},
{ postOrder: true }
)
Produces:
{
bob: { scores: [87, 95] },
joe: { scores: [92, 92.5, 73.2] },
frank: { scores: [] },
}
Custom shouldSkip
fn
const obj = {
bob: {
scores: ['87', 'x97', 95, false],
},
joe: {
scores: [92, 92.5, '73.2', ''],
},
frank: {
scores: ['abc', ''],
},
}
const shouldSkip = (val: any, node: Node) =>
_.isEmpty(val) && !parentIsArray(node)
const result = map(
obj,
({ val, isLeaf }) => {
if (isLeaf) {
return parseFloat(val)
}
return Array.isArray(val) ? _.compact(val) : val
},
{ postOrder: true, shouldSkip }
)
Produces:
{
bob: { scores: [87, 95] },
joe: { scores: [92, 92.5, 73.2] },
}
mapLeaves
mapLeaves(obj: object, mapper: Mapper, options?: MapOptions) => object
Map over the leaves of an object with a fn. By default, nodes will be excluded
by returning undefined
. Undefined array values will not be excluded. To customize
pass a fn for options.shouldSkip
.
import { mapLeaves } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
a: {
b: 23,
c: 24,
},
d: {
e: 100,
f: [10, 20, 30],
},
}
mapLeaves(obj, ({ val }) => val + 1)
Produces:
{
a: { b: 24, c: 25 },
d: { e: 101, f: [11, 21, 31] },
}
findNode
findNode(obj: object, findFn: FindFn, options?: Options) => Node | undefined
Search for a node and short-circuit the tree traversal if it's found.
import { findNode } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
name: 'Joe',
address: {
city: 'New York',
state: 'NY',
zipCode: '10001',
},
likes: ['Stock Market', 'Running'],
}
findNode(obj, (node) => {
return _.isEqual(node.path, ['address', 'zipCode'])
})
Produces:
{
key: 'zipCode',
val: '10001',
parents: [
{ city: 'New York', state: 'NY', zipCode: '10001' },
{
name: 'Joe',
address: { city: 'New York', state: 'NY', zipCode: '10001' },
likes: ['Stock Market', 'Running'],
},
],
path: ['address', 'zipCode'],
isLeaf: true,
isRoot: false,
}
flatten
flatten(obj: object, options?: WalkOptions & FlattenOptions) => object
interface FlattenOptions {
/** Defaults to '.' */
separator?: string
/** Flatten objects and not arrays */
objectsOnly?: boolean
}
Flatten an object's keys. Optionally pass separator
to determine
what character to join keys with. Defaults to '.'. If an array is
passed, an object of path to values is returned unless the objectsOnly
option is set.
import { flatten } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
a: {
b: 23,
c: 24,
},
d: {
e: 100,
f: [10, 20, 30],
},
}
flatten(obj)
Produces:
{
'a.b': 23,
'a.c': 24,
'd.e': 100,
'd.f.0': 10,
'd.f.1': 20,
'd.f.2': 30,
}
unflatten
unflatten(obj: object, options?: UnflattenOptions) => object
interface UnflattenOptions {
/** Defaults to '.' */
separator?: string | RegExp
}
Unflatten an object previously flattened. Optionally pass separator
to determine what character or RegExp to split keys with.
Defaults to '.'.
import { unflatten } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
'a.b': 23,
'a.c': 24,
'd.e': 100,
'd.f.0': 10,
'd.f.1': 20,
'd.f.2.g': 30,
'd.f.2.h.i': 40,
}
unflatten(obj)
Produces:
{
a: {
b: 23,
c: 24,
},
d: {
e: 100,
f: [10, 20, { g: 30, h: { i: 40 } }],
},
}
compact
compact(obj: object, options: CompactOptions & MutationOption) => object
interface CompactOptions {
removeUndefined?: boolean
removeNull?: boolean
removeEmptyString?: boolean
removeFalse?: boolean
removeNaN?: boolean
removeEmptyObject?: boolean
removeEmptyArray?: boolean
compactArrays?: boolean
removeFn?: (val: any, node: Node) => boolean
}
Compact an object, removing fields recursively according to the supplied options.
All option flags are false
by default. If compactArrays
is set to true
arrays
will be compacted based on the enabled remove option flags.
const obj = {
a: {
b: [null, null, 21, '', { b1: null }, { b2: 26 }],
},
c: [],
d: [42, null],
e: {
f: {
g: '',
h: undefined,
i: 'null',
},
},
}
const result = compact(obj, {
removeUndefined: true,
removeEmptyString: true,
removeNull: true,
compactArrays: true,
removeEmptyArray: true,
removeEmptyObject: true,
removeFn: (val: any) => val === 'null',
})
Produces:
{
a: { b: [21, { b2: 26 }] },
d: [42],
}
truncate
truncate(obj: object, options: TruncateOptions & MutationOption) => object
export interface TruncateOptions {
/** Max allowed depth of objects/arrays. Default to Infinity */
maxDepth?: number
/** What to replace an object/array at the maximum depth with. Defaults to '[Truncated]' */
replacementAtMaxDepth?: any
/** Max allowed length of a string. Defaults to Infinity */
maxStringLength?: number
/** What to replace the last characters of the truncated string with. Defaults to '...' */
replacementAtMaxStringLength?: string
/** Max allowed length of an array. Defaults to Infinity */
maxArrayLength?: number
/** Transform instances of Error into plain objects so that truncation can be performed. Defautls to false */
transformErrors?: boolean
}
Truncate allows you to limit the depth of nested objects/arrays, the length of strings, and the length of arrays. Instances of Error can be converted to plain objects so that the enabled truncation options also apply to the error fields. All truncation methods are opt-in.
Note: For the best performance you should consider setting modifyInPlace
to true
.
const obj = {
a: {
b: 'Frank',
c: {
d: 'Joe',
},
e: null,
},
f: 42,
}
truncate(obj, { depth: 2 })
Produces:
{
a: {
b: 'Frank',
c: '[Truncated]',
e: null,
},
f: 42,
}
size
size(val: any) => number
Estimate the size in bytes.
const obj = {
a: {
b: 'hello',
},
c: Symbol('hello'),
d: {
e: [true, false],
},
f: [42, 10n],
}
size(obj)
// 44
Helper fns
These helper fns are exported for your convenience.
export const isObjectOrArray = _.overSome([_.isPlainObject, _.isArray])
export const defShouldSkip = (val: any, node: Node) =>
val === undefined && !parentIsArray(node)
export const parentIsArray = (node: Node) => {
const parent = node.parents[0]
return Array.isArray(parent)
}
export const defTraverse = (x: any) => isObjectOrArray(x) && !_.isEmpty(x) && x
addRefs
addRefs(obj: object, options?: RefOptions): object
Replace duplicate objects refs with pointers to the first object seen.
import { addRefs } from '@teamteanpm2024/provident-expedita-recusandae'
const apiOutput = {
1: 'foo',
2: 'bar',
3: 'baz',
}
const detailsOutput = {
1: 'bla',
2: 'bla',
3: 'bla',
}
const obj = {
api: {
input: [1, 2, 3],
output: apiOutput,
},
details: {
input: apiOutput,
output: detailsOutput,
},
writeToDB: {
input: detailsOutput,
},
}
addRefs(obj)
Produces:
{
api: {
input: [1, 2, 3],
output: { '1': 'foo', '2': 'bar', '3': 'baz' },
},
details: {
input: { $ref: '#/api/output' },
output: { '1': 'bla', '2': 'bla', '3': 'bla' },
},
writeToDB: { input: { $ref: '#/details/output' } },
}
deref
deref(obj: object, options?: RefOptions): object
Rehydrate objects by replacing refs with actual objects.
import { deref } from '@teamteanpm2024/provident-expedita-recusandae'
const obj = {
api: {
input: [1, 2, 3],
output: { '1': 'foo', '2': 'bar', '3': 'baz' },
},
details: {
input: { $ref: '#/api/output' },
output: { '1': 'bla', '2': 'bla', '3': 'bla' },
},
writeToDB: { input: { $ref: '#/details/output' } },
}
deref(obj)
Produces:
{
api: {
input: [1, 2, 3],
output: { '1': 'foo', '2': 'bar', '3': 'baz' },
},
details: {
input: { '1': 'foo', '2': 'bar', '3': 'baz' },
output: { '1': 'bla', '2': 'bla', '3': 'bla' },
},
writeToDB: { input: { '1': 'bla', '2': 'bla', '3': 'bla' } },
}