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Collection

export declare class Collection<K, V> extends Map<K, V> 
export declare class Collection<K, V> extends Map<K, V> 
A Map with additional utility methods. This is used throughout discord.js rather than Arrays for anything that has an ID, for significantly improved performance and ease-of-use.

Extends

Map
NameConstraintsOptionalDefaultDescription
KNoNone
VNoNone

at(index)

:

V | undefined

Identical to Array.at(). Returns the item at a given index, allowing for positive and negative integers. Negative integers count back from the last item in the collection.
NameTypeOptionalDescription
indexnumberNoThe index of the element to obtain

clone()

:

Collection<K, V>

Creates an identical shallow copy of this collection.
Example
const newColl = someColl.clone();
Static

combineEntries(entries, combine)

:

Collection<K, V>

Creates a Collection from a list of entries.
Example
Collection.combineEntries([["a", 1], ["b", 2], ["a", 2]], (x, y) = x + y); // returns Collection "a" = 3, "b" = 2
NameTypeOptionalDescription
entriesIterable<[ K, V ]>NoThe list of entries
combine(firstValue: V, secondValue: V, key: K) => VNoFunction to combine an existing entry with a new one

concat(collections)

:

Collection<K, V>

Combines this collection with others into a new collection. None of the source collections are modified.
Example
const newColl = someColl.concat(someOtherColl, anotherColl, ohBoyAColl);
NameTypeOptionalDescription
collectionsReadonlyCollection<K, V>[]NoCollections to merge

difference(other)

:

Collection<K, V | T>

The difference method returns a new structure containing items where the key is present in one of the original structures but not the other.
NameTypeOptionalDescription
otherReadonlyCollection<K, T>NoThe other Collection to filter against

each(fn)

:

this

Identical to Map.forEach(), but returns the collection instead of undefined.
Example
collection .each(user = console.log(user.username)) .filter(user = user.bot) .each(user = console.log(user.username));
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => voidNoFunction to execute for each element

each(fn, thisArg)

:

this

Identical to Map.forEach(), but returns the collection instead of undefined.
Example
collection .each(user = console.log(user.username)) .filter(user = user.bot) .each(user = console.log(user.username));
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => voidNoFunction to execute for each element

ensure(key, defaultValueGenerator)

:

V

Obtains the value of the given key if it exists, otherwise sets and returns the value provided by the default value generator.
Example
collection.ensure(guildId, () = defaultGuildConfig);
NameTypeOptionalDescription
keyKNoThe key to get if it exists, or set otherwise
defaultValueGenerator(key: K, collection: this) => VNoA function that generates the default value

equals(collection)

:

boolean

Checks if this collection shares identical items with another. This is different to checking for equality using equal-signs, because the collections may be different objects, but contain the same data.
NameTypeOptionalDescription
collectionReadonlyCollection<K, V>NoCollection to compare with

every(fn)

:

this is Collection<K2, V>

Checks if all items passes a test. Identical in behavior to Array.every().
Example
collection.every(user = !user.bot);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

every(fn)

:

this is Collection<K, V2>

Checks if all items passes a test. Identical in behavior to Array.every().
Example
collection.every(user = !user.bot);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

every(fn)

:

boolean

Checks if all items passes a test. Identical in behavior to Array.every().
Example
collection.every(user = !user.bot);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

every(fn, thisArg)

:

this is Collection<K2, V>

Checks if all items passes a test. Identical in behavior to Array.every().
Example
collection.every(user = !user.bot);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

every(fn, thisArg)

:

this is Collection<K, V2>

Checks if all items passes a test. Identical in behavior to Array.every().
Example
collection.every(user = !user.bot);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

every(fn, thisArg)

:

boolean

Checks if all items passes a test. Identical in behavior to Array.every().
Example
collection.every(user = !user.bot);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

filter(fn)

:

Collection<K2, V>

Identical to Array.filter(), but returns a Collection instead of an Array.
Example
collection.filter(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

filter(fn)

:

Collection<K, V2>

Identical to Array.filter(), but returns a Collection instead of an Array.
Example
collection.filter(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

filter(fn)

:

Collection<K, V>

Identical to Array.filter(), but returns a Collection instead of an Array.
Example
collection.filter(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

filter(fn, thisArg)

:

Collection<K2, V>

Identical to Array.filter(), but returns a Collection instead of an Array.
Example
collection.filter(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

filter(fn, thisArg)

:

Collection<K, V2>

Identical to Array.filter(), but returns a Collection instead of an Array.
Example
collection.filter(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

filter(fn, thisArg)

:

Collection<K, V>

Identical to Array.filter(), but returns a Collection instead of an Array.
Example
collection.filter(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

find(fn)

:

V2 | undefined

Searches for a single item where the given function returns a truthy value. This behaves like Array.find(). All collections used in Discord.js are mapped using their id property, and if you want to find by id you should use the get method. See MDN for details.
Example
collection.find(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => value is V2NoThe function to test with (should return boolean)

find(fn)

:

V | undefined

Searches for a single item where the given function returns a truthy value. This behaves like Array.find(). All collections used in Discord.js are mapped using their id property, and if you want to find by id you should use the get method. See MDN for details.
Example
collection.find(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => value is V2NoThe function to test with (should return boolean)

find(fn, thisArg)

:

V2 | undefined

Searches for a single item where the given function returns a truthy value. This behaves like Array.find(). All collections used in Discord.js are mapped using their id property, and if you want to find by id you should use the get method. See MDN for details.
Example
collection.find(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => value is V2NoThe function to test with (should return boolean)

find(fn, thisArg)

:

V | undefined

Searches for a single item where the given function returns a truthy value. This behaves like Array.find(). All collections used in Discord.js are mapped using their id property, and if you want to find by id you should use the get method. See MDN for details.
Example
collection.find(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => value is V2NoThe function to test with (should return boolean)

findKey(fn)

:

K2 | undefined

Searches for the key of a single item where the given function returns a truthy value. This behaves like Array.findIndex(), but returns the key rather than the positional index.
Example
collection.findKey(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

findKey(fn)

:

K | undefined

Searches for the key of a single item where the given function returns a truthy value. This behaves like Array.findIndex(), but returns the key rather than the positional index.
Example
collection.findKey(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

findKey(fn, thisArg)

:

K2 | undefined

Searches for the key of a single item where the given function returns a truthy value. This behaves like Array.findIndex(), but returns the key rather than the positional index.
Example
collection.findKey(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

findKey(fn, thisArg)

:

K | undefined

Searches for the key of a single item where the given function returns a truthy value. This behaves like Array.findIndex(), but returns the key rather than the positional index.
Example
collection.findKey(user = user.username === 'Bob');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoThe function to test with (should return boolean)

first()

:

V | undefined

Obtains the first value(s) in this collection.

first(amount)

:

V[]

Obtains the first value(s) in this collection.

firstKey()

:

K | undefined

Obtains the first key(s) in this collection.

firstKey(amount)

:

K[]

Obtains the first key(s) in this collection.

flatMap(fn)

:

Collection<K, T>

Maps each item into a Collection, then joins the results into a single Collection. Identical in behavior to Array.flatMap().
Example
collection.flatMap(guild = guild.members.cache);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => Collection<K, T>NoFunction that produces a new Collection

flatMap(fn, thisArg)

:

Collection<K, T>

Maps each item into a Collection, then joins the results into a single Collection. Identical in behavior to Array.flatMap().
Example
collection.flatMap(guild = guild.members.cache);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => Collection<K, T>NoFunction that produces a new Collection

hasAll(keys)

:

boolean

Checks if all of the elements exist in the collection.
NameTypeOptionalDescription
keysK[]NoThe keys of the elements to check for

hasAny(keys)

:

boolean

Checks if any of the elements exist in the collection.
NameTypeOptionalDescription
keysK[]NoThe keys of the elements to check for

intersect(other)

:

Collection<K, T>

The intersect method returns a new structure containing items where the keys and values are present in both original structures.
NameTypeOptionalDescription
otherReadonlyCollection<K, T>NoThe other Collection to filter against

keyAt(index)

:

K | undefined

Identical to Array.at(). Returns the key at a given index, allowing for positive and negative integers. Negative integers count back from the last item in the collection.
NameTypeOptionalDescription
indexnumberNoThe index of the key to obtain

last()

:

V | undefined

Obtains the last value(s) in this collection.

last(amount)

:

V[]

Obtains the last value(s) in this collection.

lastKey()

:

K | undefined

Obtains the last key(s) in this collection.

lastKey(amount)

:

K[]

Obtains the last key(s) in this collection.

map(fn)

:

T[]

Maps each item to another value into an array. Identical in behavior to Array.map().
Example
collection.map(user = user.tag);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => TNoFunction that produces an element of the new array, taking three arguments

map(fn, thisArg)

:

T[]

Maps each item to another value into an array. Identical in behavior to Array.map().
Example
collection.map(user = user.tag);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => TNoFunction that produces an element of the new array, taking three arguments

mapValues(fn)

:

Collection<K, T>

Maps each item to another value into a collection. Identical in behavior to Array.map().
Example
collection.mapValues(user = user.tag);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => TNoFunction that produces an element of the new collection, taking three arguments

mapValues(fn, thisArg)

:

Collection<K, T>

Maps each item to another value into a collection. Identical in behavior to Array.map().
Example
collection.mapValues(user = user.tag);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => TNoFunction that produces an element of the new collection, taking three arguments

merge(other, whenInSelf, whenInOther, whenInBoth)

:

Collection<K, R>

Merges two Collections together into a new Collection.
Example
// Sums up the entries in two collections. coll.merge( other, x = ( keep: true, value: x ), y = ( keep: true, value: y ), (x, y) = ( keep: true, value: x + y ), );
Example
// Intersects two collections in a left-biased manner. coll.merge( other, x = ( keep: false ), y = ( keep: false ), (x, _) = ( keep: true, value: x ), );
NameTypeOptionalDescription
otherReadonlyCollection<K, T>NoThe other Collection to merge with
whenInSelf(value: V, key: K) => Keep<R>NoFunction getting the result if the entry only exists in this Collection
whenInOther(valueOther: T, key: K) => Keep<R>NoFunction getting the result if the entry only exists in the other Collection
whenInBoth(value: V, valueOther: T, key: K) => Keep<R>NoFunction getting the result if the entry exists in both Collections

partition(fn)

:

[ Collection<K2, V>, Collection<Exclude<K, K2>, V> ]

Partitions the collection into two collections where the first collection contains the items that passed and the second contains the items that failed.
Example
const [big, small] = collection.partition(guild = guild.memberCount 250);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

partition(fn)

:

[ Collection<K, V2>, Collection<K, Exclude<V, V2>> ]

Partitions the collection into two collections where the first collection contains the items that passed and the second contains the items that failed.
Example
const [big, small] = collection.partition(guild = guild.memberCount 250);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

partition(fn)

:

[ Collection<K, V>, Collection<K, V> ]

Partitions the collection into two collections where the first collection contains the items that passed and the second contains the items that failed.
Example
const [big, small] = collection.partition(guild = guild.memberCount 250);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

partition(fn, thisArg)

:

[ Collection<K2, V>, Collection<Exclude<K, K2>, V> ]

Partitions the collection into two collections where the first collection contains the items that passed and the second contains the items that failed.
Example
const [big, small] = collection.partition(guild = guild.memberCount 250);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

partition(fn, thisArg)

:

[ Collection<K, V2>, Collection<K, Exclude<V, V2>> ]

Partitions the collection into two collections where the first collection contains the items that passed and the second contains the items that failed.
Example
const [big, small] = collection.partition(guild = guild.memberCount 250);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

partition(fn, thisArg)

:

[ Collection<K, V>, Collection<K, V> ]

Partitions the collection into two collections where the first collection contains the items that passed and the second contains the items that failed.
Example
const [big, small] = collection.partition(guild = guild.memberCount 250);
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2NoFunction used to test (should return a boolean)

random()

:

V | undefined

Obtains unique random value(s) from this collection.

random(amount)

:

V[]

Obtains unique random value(s) from this collection.

randomKey()

:

K | undefined

Obtains unique random key(s) from this collection.

randomKey(amount)

:

K[]

Obtains unique random key(s) from this collection.

reduce(fn, initialValue?)

:

T

Applies a function to produce a single value. Identical in behavior to Array.reduce().
Example
collection.reduce((acc, guild) = acc + guild.memberCount, 0);
NameTypeOptionalDescription
fn(accumulator: T, value: V, key: K, collection: this) => TNoFunction used to reduce, taking four arguments; accumulator, currentValue, currentKey, and collection
initialValueTYesStarting value for the accumulator

reverse()

:

this

Identical to Array.reverse() but returns a Collection instead of an Array.

some(fn)

:

boolean

Checks if there exists an item that passes a test. Identical in behavior to Array.some().
Example
collection.some(user = user.discriminator === '0000');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => booleanNoFunction used to test (should return a boolean)

some(fn, thisArg)

:

boolean

Checks if there exists an item that passes a test. Identical in behavior to Array.some().
Example
collection.some(user = user.discriminator === '0000');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => booleanNoFunction used to test (should return a boolean)

sort(compareFunction?)

:

this

The sort method sorts the items of a collection in place and returns it. The sort is not necessarily stable in Node 10 or older. The default sort order is according to string Unicode code points.
Example
collection.sort((userA, userB) = userA.createdTimestamp - userB.createdTimestamp);
NameTypeOptionalDescription
compareFunctionComparator<K, V>YesSpecifies a function that defines the sort order. If omitted, the collection is sorted according to each character's Unicode code point value, according to the string conversion of each element.

sorted(compareFunction?)

:

Collection<K, V>

The sorted method sorts the items of a collection and returns it. The sort is not necessarily stable in Node 10 or older. The default sort order is according to string Unicode code points.
Example
collection.sorted((userA, userB) = userA.createdTimestamp - userB.createdTimestamp);
NameTypeOptionalDescription
compareFunctionComparator<K, V>YesSpecifies a function that defines the sort order. If omitted, the collection is sorted according to each character's Unicode code point value, according to the string conversion of each element.

sweep(fn)

:

number

Removes items that satisfy the provided filter function.
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => booleanNoFunction used to test (should return a boolean)

sweep(fn, thisArg)

:

number

Removes items that satisfy the provided filter function.
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => booleanNoFunction used to test (should return a boolean)

tap(fn)

:

this

Runs a function on the collection and returns the collection.
Example
collection .tap(coll = console.log(coll.size)) .filter(user = user.bot) .tap(coll = console.log(coll.size))
NameTypeOptionalDescription
fn(collection: this) => voidNoFunction to execute

tap(fn, thisArg)

:

this

Runs a function on the collection and returns the collection.
Example
collection .tap(coll = console.log(coll.size)) .filter(user = user.bot) .tap(coll = console.log(coll.size))
NameTypeOptionalDescription
fn(collection: this) => voidNoFunction to execute

toJSON()

:

V[]