Immutable Map is an unordered Collection.Keyed of (key, value) pairs with
O(log32 N) gets and O(log32 N) persistent sets.
type Map<K, V> extends Collection.Keyed<K, V>Iteration order of a Map is undefined, however is stable. Multiple iterations of the same Map will iterate in the same order.
Map's keys can be of any type, and use Immutable.is to determine key
equality. This allows the use of any value (including NaN) as a key.
Because Immutable.is returns equality based on value semantics, and
Immutable collections are treated as values, any Immutable collection may
be used as a key.
const { Map, List } = require('immutable');
Map().set(List([ 1 ]), 'listofone').get(List([ 1 ]));
// 'listofone'run itAny JavaScript object may be used as a key, however strict identity is used to evaluate key equality. Two similar looking objects will represent two different keys.
Implemented by a hash-array mapped trie.
Map.isMap(maybeMap: unknown): boolean
The number of entries in this Map.
size: numberReturns a new Map also containing the new key, value pair. If an equivalent key already exists in this Map, it will be replaced.
set(key: K, value: V): this
const { Map } = require('immutable')
const originalMap = Map()
const newerMap = originalMap.set('key', 'value')
const newestMap = newerMap.set('key', 'newer value')
originalMap
// Map {}
newerMap
// Map { "key": "value" }
newestMap
// Map { "key": "newer value" }run itNote: set can be used in withMutations.
Returns a new Map which excludes this key.
delete(key: K): this
remove()Note: delete cannot be safely used in IE8, but is provided to mirror
the ES6 collection API.
const { Map } = require('immutable')
const originalMap = Map({
key: 'value',
otherKey: 'other value'
})
// Map { "key": "value", "otherKey": "other value" }
originalMap.delete('otherKey')
// Map { "key": "value" }run itNote: delete can be used in withMutations.
Returns a new Map which excludes the provided keys.
deleteAll(keys: Iterable<K>): this
removeAll()const { Map } = require('immutable')
const names = Map({ a: "Aaron", b: "Barry", c: "Connor" })
names.deleteAll([ 'a', 'c' ])
// Map { "b": "Barry" }run it
Note: deleteAll can be used in withMutations.
Returns a new Map containing no keys or values.
clear(): this
const { Map } = require('immutable')
Map({ key: 'value' }).clear()
// Map {}run it
Note: clear can be used in withMutations.
update(key: K, notSetValue: V, updater: (value: V) => V): this
update(key: K, updater: (value: V | undefined) => V | undefined): this
update<R>(updater: (value: this) => R): R
Collection#update()Like mergeDeep(), but when two non-collections or incompatible
collections are encountered at the same key, it uses the merger
function to determine the resulting value. Collections are considered
incompatible if they fall into separate categories between keyed,
indexed, and set-like.
mergeDeepWith(merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
...collections: Array<Iterable<[K, V]> | {[key: string]: V}>): this
const { Map } = require('immutable')
const one = Map({ a: Map({ x: 10, y: 10 }), b: Map({ x: 20, y: 50 }) })
const two = Map({ a: Map({ x: 2 }), b: Map({ y: 5 }), c: Map({ z: 3 }) })
one.mergeDeepWith((oldVal, newVal) => oldVal / newVal, two)
// Map {
// "a": Map { "x": 5, "y": 10 },
// "b": Map { "x": 20, "y": 10 },
// "c": Map { "z": 3 }
// }run it
Note: mergeDeepWith can be used in withMutations.
Returns a new Map having set value at this keyPath. If any keys in
keyPath do not exist, a new immutable Map will be created at that key.
setIn(keyPath: Iterable<unknown>, value: unknown): this
const { Map } = require('immutable')
const originalMap = Map({
subObject: Map({
subKey: 'subvalue',
subSubObject: Map({
subSubKey: 'subSubValue'
})
})
})
const newMap = originalMap.setIn(['subObject', 'subKey'], 'ha ha!') // Map { // "subObject": Map { // "subKey": "ha ha!", // "subSubObject": Map { "subSubKey": "subSubValue" } // } // }
const newerMap = originalMap.setIn( ['subObject', 'subSubObject', 'subSubKey'], 'ha ha ha!' ) // Map { // "subObject": Map { // "subKey": "subvalue", // "subSubObject": Map { "subSubKey": "ha ha ha!" } // } // }run it
Plain JavaScript Object or Arrays may be nested within an Immutable.js Collection, and setIn() can update those values as well, treating them immutably by creating new copies of those values with the changes applied.
const { Map } = require('immutable')
const originalMap = Map({
subObject: {
subKey: 'subvalue',
subSubObject: {
subSubKey: 'subSubValue'
}
}
})
originalMap.setIn(['subObject', 'subKey'], 'ha ha!') // Map { // "subObject": { // subKey: "ha ha!", // subSubObject: { subSubKey: "subSubValue" } // } // }run it
If any key in the path exists but cannot be updated (such as a primitive like number or a custom Object like Date), an error will be thrown.
Note: setIn can be used in withMutations.
Returns a new Map having removed the value at this keyPath. If any keys
in keyPath do not exist, no change will occur.
deleteIn(keyPath: Iterable<unknown>): this
removeIn()Note: deleteIn can be used in withMutations.
updateIn(keyPath: Iterable<unknown>,
notSetValue: unknown,
updater: (value: unknown) => unknown): this
updateIn(keyPath: Iterable<unknown>, updater: (value: unknown) => unknown): this
A combination of updateIn and merge, returning a new Map, but
performing the merge at a point arrived at by following the keyPath.
In other words, these two lines are equivalent:
mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this
map.updateIn(['a', 'b', 'c'], abc => abc.merge(y))
map.mergeIn(['a', 'b', 'c'], y)
Note: mergeIn can be used in withMutations.
A combination of updateIn and mergeDeep, returning a new Map, but
performing the deep merge at a point arrived at by following the keyPath.
In other words, these two lines are equivalent:
mergeDeepIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this
map.updateIn(['a', 'b', 'c'], abc => abc.mergeDeep(y))
map.mergeDeepIn(['a', 'b', 'c'], y)
Note: mergeDeepIn can be used in withMutations.
Every time you call one of the above functions, a new immutable Map is created. If a pure function calls a number of these to produce a final return value, then a penalty on performance and memory has been paid by creating all of the intermediate immutable Maps.
withMutations(mutator: (mutable: this) => unknown): this
If you need to apply a series of mutations to produce a new immutable
Map, withMutations() creates a temporary mutable copy of the Map which
can apply mutations in a highly performant manner. In fact, this is
exactly how complex mutations like merge are done.
As an example, this results in the creation of 2, not 4, new Maps:
const { Map } = require('immutable')
const map1 = Map()
const map2 = map1.withMutations(map => {
map.set('a', 1).set('b', 2).set('c', 3)
})
assert.equal(map1.size, 0)
assert.equal(map2.size, 3)run itNote: Not all methods can be used on a mutable collection or within
withMutations! Read the documentation for each method to see if it
is safe to use in withMutations.
Another way to avoid creation of intermediate Immutable maps is to create
a mutable copy of this collection. Mutable copies always return this,
and thus shouldn't be used for equality. Your function should never return
a mutable copy of a collection, only use it internally to create a new
collection.
asMutable(): this
If possible, use withMutations to work with temporary mutable copies as
it provides an easier to use API and considers many common optimizations.
Note: if the collection is already mutable, asMutable returns itself.
Note: Not all methods can be used on a mutable collection or within
withMutations! Read the documentation for each method to see if it
is safe to use in withMutations.
Returns true if this is a mutable copy (see asMutable()) and mutative
alterations have been applied.
wasAltered(): boolean
The yin to asMutable's yang. Because it applies to mutable collections,
this operation is mutable and may return itself (though may not
return itself, i.e. if the result is an empty collection). Once
performed, the original mutable copy must no longer be mutated since it
may be the immutable result.
asImmutable(): this
If possible, use withMutations to work with temporary mutable copies as
it provides an easier to use API and considers many common optimizations.
Returns a new Map with values passed through a
mapper function.
map<M>(mapper: (value: V, key: K, iter: this) => M,
context?: unknown): Map<K, M>
Collection.Keyed#map()Map({ a: 1, b: 2 }).map(x => 10 * x)
// Map { a: 10, b: 20 }mapKeys<M>(mapper: (key: K, value: V, iter: this) => M,
context?: unknown): Map<M, V>
Collection.Keyed#mapKeys()Collection.Keyed.mapKeys
mapEntries<KM, VM>(mapper: (entry: [K, V], index: number, iter: this) => [KM, VM] | undefined,
context?: unknown): Map<KM, VM>
Collection.Keyed#mapEntries()Collection.Keyed.mapEntries
Flat-maps the Map, returning a new Map.
flatMap<KM, VM>(mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
context?: unknown): Map<KM, VM>
Collection.Keyed#flatMap()Similar to data.map(...).flatten(true).
filter<F>(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): Map<K, F>
filter(predicate: (value: V, key: K, iter: this) => unknown,
context?: unknown): this
Collection.Keyed#filter()partition<F, C>(predicate: (this: C, value: V, key: K, iter: this) => boolean,
context?: C): [Map<K, V>, Map<K, F>]
partition<C>(predicate: (this: C, value: V, key: K, iter: this) => unknown,
context?: C): [this, this]
Collection.Keyed#partition()Returns an OrderedMap of the same type which includes the same entries,
stably sorted by using a comparator.
sort(comparator?: Comparator<V>): this & OrderedMap<K, V>
Collection#sort()If a comparator is not provided, a default comparator uses < and >.
comparator(valueA, valueB):
0 if the elements should not be swapped.-1 (or any negative number) if valueA comes before valueB1 (or any positive number) if valueA comes after valueBPairSorting enum typeconst { Map } = require('immutable')
Map({ "c": 3, "a": 1, "b": 2 }).sort((a, b) => {
if (a < b) { return -1; }
if (a > b) { return 1; }
if (a === b) { return 0; }
});
// OrderedMap { "a": 1, "b": 2, "c": 3 }run itNote: sort() Always returns a new instance, even if the original was
already sorted.
Note: This is always an eager operation.
Like sort, but also accepts a comparatorValueMapper which allows for
sorting by more sophisticated means:
sortBy<C>(comparatorValueMapper: (value: V, key: K, iter: this) => C,
comparator?: (valueA: C, valueB: C) => number): this & OrderedMap<K, V>
Collection#sortBy()const { Map } = require('immutable')
const beattles = Map({
John: { name: "Lennon" },
Paul: { name: "McCartney" },
George: { name: "Harrison" },
Ringo: { name: "Starr" },
});
beattles.sortBy(member => member.name);run it
Note: sortBy() Always returns a new instance, even if the original was
already sorted.
Note: This is always an eager operation.
Returns a new Collection of the same type with only the entries for which
the predicate function returns false.
filterNot(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): this
Collection#filterNot()const { Map } = require('immutable')
Map({ a: 1, b: 2, c: 3, d: 4}).filterNot(x => x % 2 === 0)
// Map { "a": 1, "c": 3 }run it
Note: filterNot() always returns a new instance, even if it results in
not filtering out any values.
Returns a new Collection of the same type in reverse order.
reverse(): this
Collection#reverse()Returns a Map of Collection, grouped by the return
value of the grouper function.
groupBy<G>(grouper: (value: V, key: K, iter: this) => G,
context?: unknown): Map<G, this>
Collection#groupBy()Note: This is always an eager operation.
const { List, Map } = require('immutable')
const listOfMaps = List([
Map({ v: 0 }),
Map({ v: 1 }),
Map({ v: 1 }),
Map({ v: 0 }),
Map({ v: 2 })
])
const groupsOfMaps = listOfMaps.groupBy(x => x.get('v'))
// Map {
// 0: List [ Map{ "v": 0 }, Map { "v": 0 } ],
// 1: List [ Map{ "v": 1 }, Map { "v": 1 } ],
// 2: List [ Map{ "v": 2 } ],
// }run itDeeply converts this Keyed collection to equivalent native JavaScript Object.
toJS(): {[key: string]: DeepCopy<V>}
Collection.Keyed#toJS()Converts keys to Strings.
Shallowly converts this Keyed collection to equivalent native JavaScript Object.
toJSON(): {[key: string]: V}
Collection.Keyed#toJSON()Converts keys to Strings.
Shallowly converts this collection to an Array.
toArray(): Array<[K, V]>
Collection.Keyed#toArray()Shallowly converts this Collection to an Object.
toObject(): {[key: string]: V}
Collection#toObject()Converts keys to Strings.
Returns a Seq.Keyed from this Collection where indices are treated as keys.
toKeyedSeq(): Seq.Keyed<K, V>
Collection#toKeyedSeq()This is useful if you want to operate on an Collection.Indexed and preserve the [index, value] pairs.
The returned Seq will have identical iteration order as this Collection.
const { Seq } = require('immutable')
const indexedSeq = Seq([ 'A', 'B', 'C' ])
// Seq [ "A", "B", "C" ]
indexedSeq.filter(v => v === 'B')
// Seq [ "B" ]
const keyedSeq = indexedSeq.toKeyedSeq()
// Seq { 0: "A", 1: "B", 2: "C" }
keyedSeq.filter(v => v === 'B')
// Seq { 1: "B" }run itReturns an Seq.Indexed of the values of this Collection, discarding keys.
toIndexedSeq(): Seq.Indexed<V>
Collection#toIndexedSeq()Returns a Seq.Set of the values of this Collection, discarding keys.
toSetSeq(): Seq.Set<V>
Collection#toSetSeq()concat<KC, VC>(...collections: Array<Iterable<[KC, VC]>>): Collection.Keyed<K | KC, V | VC>
concat<C>(...collections: Array<{[key: string]: C}>): Collection.Keyed<K | string, V | C>
Collection.Keyed#concat()[Symbol.iterator](): IterableIterator<[K, V]>
Collection.Keyed#[Symbol.iterator]()True if this and the other Collection have value equality, as defined
by Immutable.is().
equals(other: unknown): boolean
Collection#equals()Note: This is equivalent to Immutable.is(this, other), but provided to
allow for chained expressions.
Computes and returns the hashed identity for this Collection.
hashCode(): number
Collection#hashCode()The hashCode of a Collection is used to determine potential equality,
and is used when adding this to a Set or as a key in a Map, enabling
lookup via a different instance.
const a = List([ 1, 2, 3 ]);
const b = List([ 1, 2, 3 ]);
assert.notStrictEqual(a, b); // different instances
const set = Set([ a ]);
assert.equal(set.has(b), true);run itIf two values have the same hashCode, they are not guaranteed
to be equal. If two values have different hashCodes,
they must not be equal.
get<NSV>(key: K, notSetValue: NSV): V | NSV
get(key: K): V | undefined
Collection#get()True if a key exists within this Collection, using Immutable.is
to determine equality
has(key: K): boolean
Collection#has()True if a value exists within this Collection, using Immutable.is
to determine equality
includes(value: V): boolean
Collection#includes()contains()first<NSV>(notSetValue: NSV): V | NSV
first(): V | undefined
Collection#first()last<NSV>(notSetValue: NSV): V | NSV
last(): V | undefined
Collection#last()Returns the value found by following a path of keys or indices through nested Collections.
getIn(searchKeyPath: Iterable<unknown>, notSetValue?: unknown): unknown
Collection#getIn()const { Map, List } = require('immutable')
const deepData = Map({ x: List([ Map({ y: 123 }) ]) });
deepData.getIn(['x', 0, 'y']) // 123run it
Plain JavaScript Object or Arrays may be nested within an Immutable.js Collection, and getIn() can access those values as well:
const { Map, List } = require('immutable')
const deepData = Map({ x: [ { y: 123 } ] });
deepData.getIn(['x', 0, 'y']) // 123run it
True if the result of following a path of keys or indices through nested Collections results in a set value.
hasIn(searchKeyPath: Iterable<unknown>): boolean
Collection#hasIn()Converts this Collection to a Map, Throws if keys are not hashable.
toMap(): Map<K, V>
Collection#toMap()Note: This is equivalent to Map(this.toKeyedSeq()), but provided
for convenience and to allow for chained expressions.
Converts this Collection to a Map, maintaining the order of iteration.
toOrderedMap(): OrderedMap<K, V>
Collection#toOrderedMap()Note: This is equivalent to OrderedMap(this.toKeyedSeq()), but
provided for convenience and to allow for chained expressions.
Converts this Collection to a Set, discarding keys. Throws if values are not hashable.
toSet(): Set<V>
Collection#toSet()Note: This is equivalent to Set(this), but provided to allow for
chained expressions.
Converts this Collection to a Set, maintaining the order of iteration and discarding keys.
toOrderedSet(): OrderedSet<V>
Collection#toOrderedSet()Note: This is equivalent to OrderedSet(this.valueSeq()), but provided
for convenience and to allow for chained expressions.
Converts this Collection to a List, discarding keys.
toList(): List<V>
Collection#toList()This is similar to List(collection), but provided to allow for chained
expressions. However, when called on Map or other keyed collections,
collection.toList() discards the keys and creates a list of only the
values, whereas List(collection) creates a list of entry tuples.
const { Map, List } = require('immutable')
var myMap = Map({ a: 'Apple', b: 'Banana' })
List(myMap) // List [ [ "a", "Apple" ], [ "b", "Banana" ] ]
myMap.toList() // List [ "Apple", "Banana" ]run itConverts this Collection to a Stack, discarding keys. Throws if values are not hashable.
toStack(): Stack<V>
Collection#toStack()Note: This is equivalent to Stack(this), but provided to allow for
chained expressions.
An iterator of this Collection's keys.
keys(): IterableIterator<K>
Collection#keys()Note: this will return an ES6 iterator which does not support
Immutable.js sequence algorithms. Use keySeq instead, if this is
what you want.
An iterator of this Collection's values.
values(): IterableIterator<V>
Collection#values()Note: this will return an ES6 iterator which does not support
Immutable.js sequence algorithms. Use valueSeq instead, if this is
what you want.
An iterator of this Collection's entries as [ key, value ] tuples.
entries(): IterableIterator<[K, V]>
Collection#entries()Note: this will return an ES6 iterator which does not support
Immutable.js sequence algorithms. Use entrySeq instead, if this is
what you want.
Returns a new Seq.Indexed of the keys of this Collection, discarding values.
keySeq(): Seq.Indexed<K>
Collection#keySeq()Returns an Seq.Indexed of the values of this Collection, discarding keys.
valueSeq(): Seq.Indexed<V>
Collection#valueSeq()Returns a new Seq.Indexed of [key, value] tuples.
entrySeq(): Seq.Indexed<[K, V]>
Collection#entrySeq()The sideEffect is executed for every entry in the Collection.
forEach(sideEffect: (value: V, key: K, iter: this) => unknown,
context?: unknown): number
Collection#forEach()Unlike Array#forEach, if any call of sideEffect returns
false, the iteration will stop. Returns the number of entries iterated
(including the last iteration which returned false).
Returns a new Collection of the same type representing a portion of this Collection from start up to but not including end.
slice(begin?: number, end?: number): this
Collection#slice()If begin is negative, it is offset from the end of the Collection. e.g.
slice(-2) returns a Collection of the last two entries. If it is not
provided the new Collection will begin at the beginning of this Collection.
If end is negative, it is offset from the end of the Collection. e.g.
slice(0, -1) returns a Collection of everything but the last entry. If
it is not provided, the new Collection will continue through the end of
this Collection.
If the requested slice is equivalent to the current Collection, then it will return itself.
Returns a new Collection of the same type containing all entries except the first.
rest(): this
Collection#rest()Returns a new Collection of the same type containing all entries except the last.
butLast(): this
Collection#butLast()Returns a new Collection of the same type which excludes the first amount
entries from this Collection.
skip(amount: number): this
Collection#skip()Returns a new Collection of the same type which excludes the last amount
entries from this Collection.
skipLast(amount: number): this
Collection#skipLast()Returns a new Collection of the same type which includes entries starting
from when predicate first returns false.
skipWhile(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): this
Collection#skipWhile()const { List } = require('immutable')
List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
.skipWhile(x => x.match(/g/))
// List [ "cat", "hat", "god" ]run it
Returns a new Collection of the same type which includes entries starting
from when predicate first returns true.
skipUntil(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): this
Collection#skipUntil()const { List } = require('immutable')
List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
.skipUntil(x => x.match(/hat/))
// List [ "hat", "god" ]run it
Returns a new Collection of the same type which includes the first amount
entries from this Collection.
take(amount: number): this
Collection#take()Returns a new Collection of the same type which includes the last amount
entries from this Collection.
takeLast(amount: number): this
Collection#takeLast()Returns a new Collection of the same type which includes entries from this
Collection as long as the predicate returns true.
takeWhile(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): this
Collection#takeWhile()const { List } = require('immutable')
List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
.takeWhile(x => x.match(/o/))
// List [ "dog", "frog" ]run it
Returns a new Collection of the same type which includes entries from this
Collection as long as the predicate returns false.
takeUntil(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): this
Collection#takeUntil()const { List } = require('immutable')
List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
.takeUntil(x => x.match(/at/))
// List [ "dog", "frog" ]run it
flatten(depth?: number): Collection<unknown, unknown>
flatten(shallow?: boolean): Collection<unknown, unknown>
Collection#flatten()reduce<R>(reducer: (reduction: R, value: V, key: K, iter: this) => R,
initialReduction: R,
context?: unknown): R
reduce<R>(reducer: (reduction: V | R, value: V, key: K, iter: this) => R): R
Collection#reduce()reduceRight<R>(reducer: (reduction: R, value: V, key: K, iter: this) => R,
initialReduction: R,
context?: unknown): R
reduceRight<R>(reducer: (reduction: V | R, value: V, key: K, iter: this) => R): R
Collection#reduceRight()True if predicate returns true for all entries in the Collection.
every(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): boolean
Collection#every()True if predicate returns true for any entry in the Collection.
some(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): boolean
Collection#some()Joins values together as a string, inserting a separator between each.
The default separator is ",".
join(separator?: string): string
Collection#join()Returns true if this Collection includes no values.
isEmpty(): boolean
Collection#isEmpty()count(): number
count(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): number
Collection#count()Returns a Seq.Keyed of counts, grouped by the return value of
the grouper function.
countBy<G>(grouper: (value: V, key: K, iter: this) => G,
context?: unknown): Map<G, number>
Collection#countBy()Note: This is not a lazy operation.
Returns the first value for which the predicate returns true.
find(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown,
notSetValue?: V): V | undefined
Collection#find()Returns the last value for which the predicate returns true.
findLast(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown,
notSetValue?: V): V | undefined
Collection#findLast()Note: predicate will be called for each entry in reverse.
Returns the first [key, value] entry for which the predicate returns true.
findEntry(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown,
notSetValue?: V): [K, V] | undefined
Collection#findEntry()Returns the last [key, value] entry for which the predicate
returns true.
findLastEntry(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown,
notSetValue?: V): [K, V] | undefined
Collection#findLastEntry()Note: predicate will be called for each entry in reverse.
Returns the key for which the predicate returns true.
findKey(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): K | undefined
Collection#findKey()Returns the last key for which the predicate returns true.
findLastKey(predicate: (value: V, key: K, iter: this) => boolean,
context?: unknown): K | undefined
Collection#findLastKey()Note: predicate will be called for each entry in reverse.
Returns the key associated with the search value, or undefined.
keyOf(searchValue: V): K | undefined
Collection#keyOf()Returns the last key associated with the search value, or undefined.
lastKeyOf(searchValue: V): K | undefined
Collection#lastKeyOf()Returns the maximum value in this collection. If any values are comparatively equivalent, the first one found will be returned.
max(comparator?: Comparator<V>): V | undefined
Collection#max()The comparator is used in the same way as Collection#sort. If it is not
provided, the default comparator is >.
When two values are considered equivalent, the first encountered will be
returned. Otherwise, max will operate independent of the order of input
as long as the comparator is commutative. The default comparator > is
commutative only when types do not differ.
If comparator returns 0 and either value is NaN, undefined, or null,
that value will be returned.
Like max, but also accepts a comparatorValueMapper which allows for
comparing by more sophisticated means:
maxBy<C>(comparatorValueMapper: (value: V, key: K, iter: this) => C,
comparator?: Comparator<C>): V | undefined
Collection#maxBy()const { List, } = require('immutable');
const l = List([
{ name: 'Bob', avgHit: 1 },
{ name: 'Max', avgHit: 3 },
{ name: 'Lili', avgHit: 2 } ,
]);
l.maxBy(i => i.avgHit); // will output { name: 'Max', avgHit: 3 }run it
Returns the minimum value in this collection. If any values are comparatively equivalent, the first one found will be returned.
min(comparator?: Comparator<V>): V | undefined
Collection#min()The comparator is used in the same way as Collection#sort. If it is not
provided, the default comparator is <.
When two values are considered equivalent, the first encountered will be
returned. Otherwise, min will operate independent of the order of input
as long as the comparator is commutative. The default comparator < is
commutative only when types do not differ.
If comparator returns 0 and either value is NaN, undefined, or null,
that value will be returned.
Like min, but also accepts a comparatorValueMapper which allows for
comparing by more sophisticated means:
minBy<C>(comparatorValueMapper: (value: V, key: K, iter: this) => C,
comparator?: Comparator<C>): V | undefined
Collection#minBy()const { List, } = require('immutable');
const l = List([
{ name: 'Bob', avgHit: 1 },
{ name: 'Max', avgHit: 3 },
{ name: 'Lili', avgHit: 2 } ,
]);
l.minBy(i => i.avgHit); // will output { name: 'Bob', avgHit: 1 }run it
True if iter includes every value in this Collection.
isSubset(iter: Iterable<V>): boolean
Collection#isSubset()True if this Collection includes every value in iter.
isSuperset(iter: Iterable<V>): boolean
Collection#isSuperset()