Object-Scan

Traverse object hierarchies using matching and callbacks.

Install

Install with npm:

$ npm install --save object-scan

Usage

import objectScan from 'object-scan';

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' } } };
objectScan(['a.*.f'], { joined: true })(haystack);
// => [ 'a.e.f' ]

Features

Input traversed exactly once during search
Dependency free, small in size and very performant
Separate Object and Array matching
Wildcard and Regex matching
Arbitrary depth matching
Or-clause Syntax
Exclusion Matching
Full support for escaping
Traversal in "delete-safe" order
Recursion free implementation
Search syntax validated
Lots of tests and examples

Matching

A needle expression specifies one or more paths to an element (or a set of elements) in a JSON structure. Paths use the dot notation:

store.book[0].title

Array

Rectangular brackets for array path matching.

Examples:

['[2]'] (exact in array)

const haystack = [0, 1, 2, 3, 4];
objectScan(['[2]'], { joined: true })(haystack);
// => [ '[2]' ]

['[1]'] (no match in object)

const haystack = { 0: 'a', 1: 'b', 2: 'c' };
objectScan(['[1]'], { joined: true })(haystack);
// => []

Object

Property name for object property matching.

Examples:

['foo'] (exact in object)

const haystack = { foo: 0, bar: 1 };
objectScan(['foo'], { joined: true })(haystack);
// => [ 'foo' ]

['1'] (no match in array)

const haystack = [0, 1, 2, 3, 4];
objectScan(['1'], { joined: true })(haystack);
// => []

Wildcard

The following characters have special meaning when not escaped:

*: Match zero or more character
+: Match one or more character
?: Match exactly one character
\: Escape the subsequent character

Wildcards can be used with Array and Object selector.

Examples:

['*'] (top level)

const haystack = { a: { b: 0, c: 1 }, d: 2 };
objectScan(['*'], { joined: true })(haystack);
// => [ 'd', 'a' ]

['[?5]'] (two digit ending in five)

const haystack = [...Array(30).keys()];
objectScan(['[?5]'], { joined: true })(haystack);
// => [ '[25]', '[15]' ]

['a.+.c'] (nested)

const haystack = { a: { b: { c: 0 }, d: { f: 0 } } };
objectScan(['a.+.c'], { joined: true })(haystack);
// => [ 'a.b.c' ]

['a.\\+.c'] (escaped)

const haystack = { a: { b: { c: 0 }, '+': { c: 0 } } };
objectScan(['a.\\+.c'], { joined: true })(haystack);
// => [ 'a.\\+.c' ]

Regex

Regex are defined by using parentheses.

Can be used with Array and Object selector.

Examples:

['(^foo)'] (starting with `foo`)

const haystack = { foo: 0, foobar: 1, bar: 2 };
objectScan(['(^foo)'], { joined: true })(haystack);
// => [ 'foobar', 'foo' ]

['[(5)]'] (containing `5`)

const haystack = [...Array(20).keys()];
objectScan(['[(5)]'], { joined: true })(haystack);
// => [ '[15]', '[5]' ]

['[(^[01]$)]'] (`[0]` and `[1]`)

const haystack = ['a', 'b', 'c', 'd'];
objectScan(['[(^[01]$)]'], { joined: true })(haystack);
// => [ '[1]', '[0]' ]

['[(^[^01]$)]'] (other than `[0]` and `[1]`)

const haystack = ['a', 'b', 'c', 'd'];
objectScan(['[(^[^01]$)]'], { joined: true })(haystack);
// => [ '[3]', '[2]' ]

['[*]', '[!(^[01]$)]'] (match all and exclude `[0]` and `[1]`)

const haystack = ['a', 'b', 'c', 'd'];
objectScan(['[*]', '[!(^[01]$)]'], { joined: true })(haystack);
// => [ '[3]', '[2]' ]

Arbitrary Depth

There are two types of arbitrary depth matching:

**: Matches zero or more nestings
++: Matches one or more nestings

Recursions can be combined with a regex or a group by appending the regex or group.

Examples:

['a.**'] (zero or more nestings under `a`)

const haystack = { a: { b: 0, c: 0 } };
objectScan(['a.**'], { joined: true })(haystack);
// => [ 'a.c', 'a.b', 'a' ]

['a.++'] (one or more nestings under `a`)

const haystack = { a: { b: 0, c: 0 } };
objectScan(['a.++'], { joined: true })(haystack);
// => [ 'a.c', 'a.b' ]

['**(1)'] (all containing `1` at every level)

const haystack = { 1: { 1: ['c', 'd'] }, 510: 'e', foo: { 1: 'f' } };
objectScan(['**(1)'], { joined: true })(haystack);
// => [ '510', '1.1[1]', '1.1', '1' ]

Or Clause

Or Clauses are defined by using curley brackets.

Can be used with Array and Object selector.

Examples:

['[{0,1}]'] (`[0]` and `[1]`)

const haystack = ['a', 'b', 'c', 'd'];
objectScan(['[{0,1}]'], { joined: true })(haystack);
// => [ '[1]', '[0]' ]

['{a,d}.{b,f}'] (`a.b`, `a.f`, `d.b` and `d.f`)

const haystack = { a: { b: 0, c: 1 }, d: { e: 2, f: 3 } };
objectScan(['{a,d}.{b,f}'], { joined: true })(haystack);
// => [ 'd.f', 'a.b' ]

Nested Path Recursion

To match a nested path recursively, combine arbitrary depth matching with an or-clause.

There are two types of nested path matching:

**{...}: Matches path(s) in group zero or more times
++{...}: Matches path(s) in group one or more times

Examples:

['++{[0][1]}'] (`cyclic path`)

const haystack = [[[[0, 1], [1, 2]], [[3, 4], [5, 6]]], [[[7, 8], [9, 10]], [[11, 12], [13, 14]]]];
objectScan(['++{[0][1]}'], { joined: true })(haystack);
// => [ '[0][1][0][1]', '[0][1]' ]

['++{[0],[1]}'] (`nested or`)

const haystack = [[0, 1, 2], [3, 4, 5], [6, 7, 8]];
objectScan(['++{[0],[1]}'], { joined: true })(haystack);
// => [ '[1][1]', '[1][0]', '[1]', '[0][1]', '[0][0]', '[0]' ]

['**{[*]}'] (`traverse only array`)

const haystack = [[[{ a: [1] }], [2]]];
objectScan(['**{[*]}'], { joined: true })(haystack);
// => [ '[0][1][0]', '[0][1]', '[0][0][0]', '[0][0]', '[0]' ]

['**{*}'] (`traverse only object`)

const haystack = { a: [0, { b: 1 }], c: { d: 2 } };
objectScan(['**{*}'], { joined: true })(haystack);
// => [ 'c.d', 'c', 'a' ]

['a.**{b.c}'] (`zero or more times`)

const haystack = { a: { b: { c: { b: { c: 0 } } } } };
objectScan(['a.**{b.c}'], { joined: true })(haystack);
// => [ 'a.b.c.b.c', 'a.b.c', 'a' ]

['a.++{b.c}'] (`one or more times`)

const haystack = { a: { b: { c: { b: { c: 0 } } } } };
objectScan(['a.++{b.c}'], { joined: true })(haystack);
// => [ 'a.b.c.b.c', 'a.b.c' ]

Exclusion

To exclude a path, use exclamation mark.

Examples:

['{a,b},!a'] (only `b`)

const haystack = { a: 0, b: 1 };
objectScan(['{a,b},!a'], {
  joined: true,
  strict: false
})(haystack);
// => [ 'b' ]

['**,!**.a'] (all except ending in `a`)

const haystack = { a: 0, b: { a: 1, c: 2 } };
objectScan(['**,!**.a'], { joined: true })(haystack);
// => [ 'b.c', 'b' ]

Escaping

The following characters are considered special and need to be escaped using \, if they should be matched in a key:
[, ], {, }, (, ), ,, ., !, ?, *, + and \.

Examples:

['\\[1\\]'] (special object key)

const haystack = { '[1]': 0 };
objectScan(['\\[1\\]'], { joined: true })(haystack);
// => [ '\\[1\\]' ]

Options

Signature of all callbacks is

Fn({ key, value, ... })

where:

key: key that callback is invoked for (respects joined option).
value: value for key.
entry: entry consisting of [key, value].
property: current parent property.
gproperty: current grandparent property.
parent: current parent.
gparent: current grandparent.
parents: array of form [parent, grandparent, ...].
isMatch: true iff last targeting needle exists and is non-excluding.
matchedBy: all non-excluding needles targeting key.
excludedBy: all excluding needles targeting key.
traversedBy: all needles involved in traversing key.
isCircular: true iff value contained in parents
isLeaf: true iff value can not be traversed
depth: length of key
result: intermittent result as defined by rtn
getKey: function that returns key
getValue: function that returns value
getEntry: function that returns entry
getProperty: function that returns property
getGproperty: function that returns gproperty
getParent: function that returns parent
getGparent: function that returns gparent
getParents: function that returns parents
getIsMatch: function that returns isMatch
getMatchedBy: function that returns matchedBy
getExcludedBy: function that returns excludedBy
getTraversedBy: function that returns traversedBy
getIsCircular: function that returns isCircular
getIsLeaf: function that returns isLeaf
getDepth: function that returns depth
getResult: function that returns result
context: as passed into the search

Notes on Performance:

Arguments backed by getters use Functions Getter and should be accessed via destructuring to prevent redundant computation.
Getters should be used to improve performance for conditional access. E.g. if (isMatch) { getParents() ... }.
For performance reasons, the same object is passed to all callbacks.

filterFn

Type: function
Default: undefined

When defined, this callback is invoked for every match. If false is returned, the current key is excluded from the result.

The return value of this callback has no effect when a search context is provided.

Can be used to do processing as matching keys are traversed.

Invoked in same order as matches would appear in result.

This method is conceptually similar to Array.filter().

Examples:

['**'] (filter function)

const haystack = { a: 0, b: 'bar' };
objectScan(['**'], {
  joined: true,
  filterFn: ({ value }) => typeof value === 'string'
})(haystack);
// => [ 'b' ]

breakFn

Type: function
Default: undefined

When defined, this callback is invoked for every key that is traversed by the search. If true is returned, all keys nested under the current key are skipped in the search and from the final result.

Note that breakFn is invoked before the corresponding filterFn might be invoked.

Examples:

['**'] (break function)

const haystack = { a: { b: { c: 0 } } };
objectScan(['**'], {
  joined: true,
  breakFn: ({ key }) => key === 'a.b'
})(haystack);
// => [ 'a.b', 'a' ]

beforeFn

Type: function
Default: undefined

When defined, this function is called before traversal as beforeFn(state = { haystack, context }).

If a value other than undefined is returned from beforeFn, that value is written to state.haystack before traversal.

The content of state can be modified in the function. After beforeFn has executed, the traversal happens using state.haystack and state.context.

The content in state can be accessed in afterFn. Note however that the key result is being overwritten.

Examples:

['**'] (combining haystack and context)

const haystack = { a: 0 };
objectScan(['**'], {
  joined: true,
  beforeFn: ({ haystack: h, context: c }) => [h, c],
  rtn: 'key'
})(haystack, { b: 0 });
// => [ '[1].b', '[1]', '[0].a', '[0]' ]

['**'] (pre-processing haystack)

const haystack = { a: 0, b: 1 };
objectScan(['**'], {
  joined: true,
  beforeFn: ({ haystack: h }) => Object.keys(h),
  rtn: ['key', 'value']
})(haystack);
// => [ [ '[1]', 'b' ], [ '[0]', 'a' ] ]

afterFn

Type: function
Default: undefined

When defined, this function is called after traversal as afterFn(state = { result, haystack, context }).

Additional information written to state in beforeFn is available in afterFn.

The content of state can be modified in the function. In particular the key state.result can be updated.

If a value other than undefined is returned from afterFn, that value is written to state.result.

After beforeFn has executed, the key state.result is returned as the final result.

Examples:

['**'] (returning count plus context)

const haystack = { a: 0 };
objectScan(['**'], {
  afterFn: ({ result, context }) => result + context,
  rtn: 'count'
})(haystack, 5);
// => 6

['**'] (post-processing result)

const haystack = { a: 0, b: 3, c: 4 };
objectScan(['**'], {
  afterFn: ({ result }) => result.filter((v) => v > 3),
  rtn: 'value'
})(haystack);
// => [ 4 ]

['**'] (pass data from beforeFn to afterFn)

const haystack = {};
objectScan(['**'], {
  beforeFn: (state) => { /* eslint-disable no-param-reassign */ state.custom = 7; },
  afterFn: (state) => state.custom
})(haystack);
// => 7

compareFn

Type: function
Default: undefined

This function has the same signature as the callback functions. When defined it is expected to return a function or undefined.

The returned value is used as a comparator to determine the traversal order of any object keys.

This works together with the reverse option.

Examples:

['**'] (simple sort)

const haystack = { a: 0, c: 1, b: 2 };
objectScan(['**'], {
  joined: true,
  compareFn: () => (k1, k2) => k1.localeCompare(k2),
  reverse: false
})(haystack);
// => [ 'a', 'b', 'c' ]

reverse

Type: boolean
Default: true

When set to true, the scan is performed in reverse order. This means breakFn is executed in reverse post-order and filterFn in reverse pre-order. Otherwise breakFn is executed in pre-order and filterFn in post-order.

When reverse is true the scan is delete-safe. I.e. property can be deleted / spliced from parent object / array in filterFn.

Examples:

['**'] (breakFn, reverse true)

const haystack = { f: { b: { a: {}, d: { c: {}, e: {} } }, g: { i: { h: {} } } } };
objectScan(['**'], {
  breakFn: ({ isMatch, property, context }) => { if (isMatch) { context.push(property); } },
  reverse: true
})(haystack, []);
// => [ 'f', 'g', 'i', 'h', 'b', 'd', 'e', 'c', 'a' ]

['**'] (filterFn, reverse true)

const haystack = { f: { b: { a: {}, d: { c: {}, e: {} } }, g: { i: { h: {} } } } };
objectScan(['**'], {
  filterFn: ({ property, context }) => { context.push(property); },
  reverse: true
})(haystack, []);
// => [ 'h', 'i', 'g', 'e', 'c', 'd', 'a', 'b', 'f' ]

['**'] (breakFn, reverse false)

const haystack = { f: { b: { a: {}, d: { c: {}, e: {} } }, g: { i: { h: {} } } } };
objectScan(['**'], {
  breakFn: ({ isMatch, property, context }) => { if (isMatch) { context.push(property); } },
  reverse: false
})(haystack, []);
// => [ 'f', 'b', 'a', 'd', 'c', 'e', 'g', 'i', 'h' ]

['**'] (filterFn, reverse false)

const haystack = { f: { b: { a: {}, d: { c: {}, e: {} } }, g: { i: { h: {} } } } };
objectScan(['**'], {
  filterFn: ({ property, context }) => { context.push(property); },
  reverse: false
})(haystack, []);
// => [ 'a', 'c', 'e', 'd', 'b', 'h', 'i', 'g', 'f' ]

orderByNeedles

Type: boolean
Default: false

When set to false, all targeted keys are traversed and matched in the order determined by the compareFn and reverse option.

When set to true, all targeted keys are traversed and matched in the order determined by the corresponding needles, falling back to the above ordering.

Note that this option is constraint by the depth-first search approach.

Examples:

['c', 'a', 'b'] (order by needle)

const haystack = { a: 0, b: 1, c: 1 };
objectScan(['c', 'a', 'b'], {
  joined: true,
  orderByNeedles: true
})(haystack);
// => [ 'c', 'a', 'b' ]

['b', '*'] (fallback reverse)

const haystack = { a: 0, b: 1, c: 1 };
objectScan(['b', '*'], {
  joined: true,
  reverse: true,
  orderByNeedles: true
})(haystack);
// => [ 'b', 'c', 'a' ]

['b', '*'] (fallback not reverse)

const haystack = { a: 0, b: 1, c: 1 };
objectScan(['b', '*'], {
  joined: true,
  reverse: false,
  orderByNeedles: true
})(haystack);
// => [ 'b', 'a', 'c' ]

['a', 'b.c', 'd'] (nested match)

const haystack = { a: 0, b: { c: 1 }, d: 2 };
objectScan(['a', 'b.c', 'd'], {
  joined: true,
  orderByNeedles: true
})(haystack);
// => [ 'a', 'b.c', 'd' ]

['b', 'a', 'b.c', 'd'] (matches traverse first)

const haystack = { a: 0, b: { c: 1 }, d: 2 };
objectScan(['b', 'a', 'b.c', 'd'], {
  joined: true,
  orderByNeedles: true
})(haystack);
// => [ 'b.c', 'b', 'a', 'd' ]

abort

Type: boolean
Default: false

When set to true the scan immediately returns after the first match.

Examples:

['a', 'b'] (only return first property)

const haystack = { a: 0, b: 1 };
objectScan(['a', 'b'], {
  rtn: 'property',
  abort: true
})(haystack);
// => 'b'

['[0]', '[1]'] (abort changes count)

const haystack = ['a', 'b'];
objectScan(['[0]', '[1]'], {
  rtn: 'count',
  abort: true
})(haystack);
// => 1

rtn

Type: string or array or function
Default: dynamic

Defaults to key when search context is undefined and to context otherwise.

Can be explicitly set as a string:

context: search context is returned
key: as passed into filterFn
value: as passed into filterFn
entry: as passed into filterFn
property: as passed into filterFn
gproperty: as passed into filterFn
parent: as passed into filterFn
gparent: as passed into filterFn
parents: as passed into filterFn
isMatch: as passed into filterFn
matchedBy: as passed into filterFn
excludedBy: as passed into filterFn
traversedBy: as passed into filterFn
isCircular: as passed into filterFn
isLeaf: as passed into filterFn
depth: as passed into filterFn
bool: returns true iff a match is found
count: returns the match count

When set to array, can contain any of the above except context, bool and count.

When set to function, called with callback signature for every match. Returned value is added to the result.

When abort is set to true and rtn is not context, bool or count, the first entry of the result or undefined is returned.

Examples:

['[*]'] (return values)

const haystack = ['a', 'b', 'c'];
objectScan(['[*]'], { rtn: 'value' })(haystack);
// => [ 'c', 'b', 'a' ]

['foo[*]'] (return entries)

const haystack = { foo: ['bar'] };
objectScan(['foo[*]'], { rtn: 'entry' })(haystack);
// => [ [ [ 'foo', 0 ], 'bar' ] ]

['a.b.c', 'a'] (return properties)

const haystack = { a: { b: { c: 0 } } };
objectScan(['a.b.c', 'a'], { rtn: 'property' })(haystack);
// => [ 'c', 'a' ]

['a.b', 'a.c'] (checks for any match, full scan)

const haystack = { a: { b: 0, c: 1 } };
objectScan(['a.b', 'a.c'], { rtn: 'bool' })(haystack);
// => true

['**'] (return not provided context)

const haystack = { a: 0 };
objectScan(['**'], { rtn: 'context' })(haystack);
// => undefined

['a.b.{c,d}'] (return keys with context passed)

const haystack = { a: { b: { c: 0, d: 1 } } };
objectScan(['a.b.{c,d}'], { rtn: 'key' })(haystack, []);
// => [ [ 'a', 'b', 'd' ], [ 'a', 'b', 'c' ] ]

['a.b.{c,d}'] (return custom array)

const haystack = { a: { b: { c: 0, d: 1 } } };
objectScan(['a.b.{c,d}'], { rtn: ['property', 'value'] })(haystack, []);
// => [ [ 'd', 1 ], [ 'c', 0 ] ]

['**'] (return value plus one)

const haystack = { a: { b: { c: 0, d: 1 } } };
objectScan(['**'], {
  filterFn: ({ isLeaf }) => isLeaf,
  rtn: ({ value }) => value + 1
})(haystack);
// => [ 2, 1 ]

joined

Type: boolean
Default: false

Keys are returned as a string when set to true instead of as a list.

Setting this option to true will negatively impact performance.

Note that _.get and _.set fully support lists.

Examples:

['[*]', '[*].foo'] (joined)

const haystack = [0, 1, { foo: 'bar' }];
objectScan(['[*]', '[*].foo'], { joined: true })(haystack);
// => [ '[2].foo', '[2]', '[1]', '[0]' ]

['[*]', '[*].foo'] (not joined)

const haystack = [0, 1, { foo: 'bar' }];
objectScan(['[*]', '[*].foo'])(haystack);
// => [ [ 2, 'foo' ], [ 2 ], [ 1 ], [ 0 ] ]

useArraySelector

Type: boolean
Default: true

When set to false, no array selectors should be used in any needles and arrays are automatically traversed.

Note that the results still include the array selectors.

Examples:

['a', 'b.d'] (automatic array traversal)

const haystack = [{ a: 0 }, { b: [{ c: 1 }, { d: 2 }] }];
objectScan(['a', 'b.d'], {
  joined: true,
  useArraySelector: false
})(haystack);
// => [ '[1].b[1].d', '[0].a' ]

[''] (top level array matching)

const haystack = [{ a: 0 }, { b: 1 }];
objectScan([''], {
  joined: true,
  useArraySelector: false
})(haystack);
// => [ '[1]', '[0]' ]

strict

Type: boolean
Default: true

When set to true, errors are thrown when:

a path is identical to a previous path
a path invalidates a previous path
a path contains consecutive recursions

Examples:

['a.b', 'a.b'] (identical)

const haystack = [];
objectScan(['a.b', 'a.b'], { joined: true })(haystack);
// => 'Error: Redundant Needle Target: "a.b" vs "a.b"'

['a.{b,b}'] (identical, same needle)

const haystack = [];
objectScan(['a.{b,b}'], { joined: true })(haystack);
// => 'Error: Redundant Needle Target: "a.{b,b}" vs "a.{b,b}"'

['a.b', 'a.**'] (invalidates previous)

const haystack = [];
objectScan(['a.b', 'a.**'], { joined: true })(haystack);
// => 'Error: Needle Target Invalidated: "a.b" by "a.**"'

['**.!**'] (consecutive recursion)

const haystack = [];
objectScan(['**.!**'], { joined: true })(haystack);
// => 'Error: Redundant Recursion: "**.!**"'

Search Context

A context can be passed into a search invocation as a second parameter. It is available in all callbacks and can be used to manage state across a search invocation without having to recompile the search.

By default all matched keys are returned from a search invocation. However, when it is not undefined, the context is returned instead.

Examples:

['**.{c,d,e}'] (sum values)

const haystack = { a: { b: { c: 2, d: 11 }, e: 7 } };
objectScan(['**.{c,d,e}'], {
  joined: true,
  filterFn: ({ value, context }) => { context.sum += value; }
})(haystack, { sum: 0 });
// => { sum: 20 }

Examples

More extensive examples can be found in the tests.

['a.*.f'] (nested)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['a.*.f'], { joined: true })(haystack);
// => [ 'a.e.f' ]

['*.*.*'] (multiple nested)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['*.*.*'], { joined: true })(haystack);
// => [ 'a.e.f', 'a.b.c' ]

['a.*.{c,f}'] (or filter)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['a.*.{c,f}'], { joined: true })(haystack);
// => [ 'a.e.f', 'a.b.c' ]

['a.*.{c,f}'] (or filter, not joined)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['a.*.{c,f}'])(haystack);
// => [ [ 'a', 'e', 'f' ], [ 'a', 'b', 'c' ] ]

['*.*[*]'] (list filter)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['*.*[*]'], { joined: true })(haystack);
// => [ 'a.h[1]', 'a.h[0]' ]

['*[*]'] (list filter, unmatched)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['*[*]'], { joined: true })(haystack);
// => []

['**'] (star recursion)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['**'], { joined: true })(haystack);
// => [ 'k', 'a.h[1]', 'a.h[0]', 'a.h', 'a.e.f', 'a.e', 'a.b.c', 'a.b', 'a' ]

['++.++'] (plus recursion)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['++.++'], { joined: true })(haystack);
// => [ 'a.h[1]', 'a.h[0]', 'a.h', 'a.e.f', 'a.e', 'a.b.c', 'a.b' ]

['**.f'] (star recursion ending in f)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['**.f'], { joined: true })(haystack);
// => [ 'a.e.f' ]

['**[*]'] (star recursion ending in array)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['**[*]'], { joined: true })(haystack);
// => [ 'a.h[1]', 'a.h[0]' ]

['a.*,!a.e'] (exclusion filter)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['a.*,!a.e'], { joined: true })(haystack);
// => [ 'a.h', 'a.b' ]

['**.(^[bc]$)'] (regex matching)

const haystack = { a: { b: { c: 'd' }, e: { f: 'g' }, h: ['i', 'j'] }, k: 'l' };
objectScan(['**.(^[bc]$)'], { joined: true })(haystack);
// => [ 'a.b.c', 'a.b' ]

Edge Cases

Top level object(s) are matched by the empty needle ''. This is useful for matching objects nested in arrays by setting useArraySelector to false. To match the actual empty string as a key, use (^$).

Note that the empty string does not work to match top level objects with _.get or _.set.

Examples:

[''] (match top level objects in array)

const haystack = [{}, {}];
objectScan([''], {
  joined: true,
  useArraySelector: false
})(haystack);
// => [ '[1]', '[0]' ]

[''] (match top level object)

const haystack = {};
objectScan([''], { joined: true })(haystack);
// => [ '' ]

['**.(^$)'] (match empty string keys)

const haystack = { '': 0, a: { '': 1 } };
objectScan(['**.(^$)'])(haystack);
// => [ [ 'a', '' ], [ '' ] ]

['**(^a$)'] (star recursion matches roots)

const haystack = [0, [{ a: 1 }, 2]];
objectScan(['**(^a$)'], {
  joined: true,
  useArraySelector: false
})(haystack);
// => [ '[1][1]', '[1][0].a', '[1][0]', '[0]' ]

Internals

Conceptually this package works as follows:

During initialization the needles are parsed and built into a search tree. Various information is pre-computed and stored for every node. Finally the search function is returned.
When the search function is invoked, the input is traversed simultaneously with the relevant nodes of the search tree. Processing multiple search tree branches in parallel allows for a single traversal of the input.

Having a separate initialization stage allows for a performant search and significant speed ups when applying the same search to different input.

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README.md

README.md

Object-Scan

Install

Usage

Features

Matching

Array

Object

Wildcard

Regex

Arbitrary Depth

Or Clause

Nested Path Recursion

Exclusion

Escaping

Options

filterFn

breakFn

beforeFn

afterFn

compareFn

reverse

orderByNeedles

abort

rtn

joined

useArraySelector

strict

Search Context

Examples

Edge Cases

Internals

Files

README.md

Latest commit

History

README.md

File metadata and controls

Object-Scan

Install

Usage

Features

Matching

Array

Object

Wildcard

Regex

Arbitrary Depth

Or Clause

Nested Path Recursion

Exclusion

Escaping

Options

filterFn

breakFn

beforeFn

afterFn

compareFn

reverse

orderByNeedles

abort

rtn

joined

useArraySelector

strict

Search Context

Examples

Edge Cases

Internals