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<K, V>
NameConstraintsOptionalDefaultDescription
KNo
The key type this collection holds
VNo
The value type this collection holds
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
indexnumberNo
The index of the element to obtain
clone():Collection<K, V>
Creates an identical shallow copy of this collection.
Example
const newColl = someColl.clone();
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 }
Collection.combineEntries([["a", 1], ["b", 2], ["a", 2]], (x, y) => x + y);
// returns Collection { "a" => 3, "b" => 2 }
NameConstraintsOptionalDefaultDescription
KNoNone
VNoNone
NameTypeOptionalDescription
entriesIterable<[K, V]>No
The list of entries
combine(firstValue: V, secondValue: V, key: K) => VNo
Function 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);
const newColl = someColl.concat(someOtherColl, anotherColl, ohBoyAColl);
NameTypeOptionalDescription
collectionsReadonlyCollection<K, V>[]No
Collections to merge
difference(other):Collection<K, T | V>
The difference method returns a new structure containing items where the key is present in one of the original structures but not the other.
NameConstraintsOptionalDefaultDescription
TNoNone
NameTypeOptionalDescription
otherReadonlyCollection<K, T>No
The 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));
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) => voidNo
Function 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);
collection.ensure(guildId, () => defaultGuildConfig);
NameTypeOptionalDescription
keyKNo
The key to get if it exists, or set otherwise
defaultValueGenerator(key: K, collection: this) => VNo
A 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.
Returns
Whether the collections have identical contents
NameTypeOptionalDescription
collectionReadonlyCollection<K, V>No
Collection 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);
collection.every(user => !user.bot);
NameConstraintsOptionalDefaultDescription
K2KNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2No
Function 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');
collection.filter(user => user.username === 'Bob');
NameConstraintsOptionalDefaultDescription
K2KNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2No
The 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');
collection.find(user => user.username === 'Bob');
NameConstraintsOptionalDefaultDescription
V2VNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => value is V2No
The 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');
collection.findKey(user => user.username === 'Bob');
NameConstraintsOptionalDefaultDescription
K2KNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2No
The function to test with (should return boolean)
first():V | undefined
Obtains the first value(s) in this collection.
Returns
A single value if no amount is provided or an array of values, starting from the end if amount is negative
firstKey():K | undefined
Obtains the first key(s) in this collection.
Returns
A single key if no amount is provided or an array of keys, starting from the end if amount is negative
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);
collection.flatMap(guild => guild.members.cache);
NameConstraintsOptionalDefaultDescription
TNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => Collection<K, T>No
Function that produces a new Collection
hasAll(keys):boolean
Checks if all of the elements exist in the collection.
Returns
true if all of the elements exist, false if at least one does not exist.
NameTypeOptionalDescription
keysK[]No
The keys of the elements to check for
hasAny(keys):boolean
Checks if any of the elements exist in the collection.
Returns
true if any of the elements exist, false if none exist.
NameTypeOptionalDescription
keysK[]No
The 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.
NameConstraintsOptionalDefaultDescription
TNoNone
NameTypeOptionalDescription
otherReadonlyCollection<K, T>No
The 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
indexnumberNo
The index of the key to obtain
last():V | undefined
Obtains the last value(s) in this collection.
Returns
A single value if no amount is provided or an array of values, starting from the start if amount is negative
lastKey():K | undefined
Obtains the last key(s) in this collection.
Returns
A single key if no amount is provided or an array of keys, starting from the start if amount is negative
map(fn):T[]
Maps each item to another value into an array. Identical in behavior to Array.map().
Example
collection.map(user => user.tag);
collection.map(user => user.tag);
NameConstraintsOptionalDefaultDescription
TNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => TNo
Function 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);
collection.mapValues(user => user.tag);
NameConstraintsOptionalDefaultDescription
TNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => TNo
Function 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 }),
);
// 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 }),
);
// Intersects two collections in a left-biased manner.
coll.merge(
other,
x => ({ keep: false }),
y => ({ keep: false }),
(x, _) => ({ keep: true, value: x }),
);
NameConstraintsOptionalDefaultDescription
TNoNone
RNoNone
NameTypeOptionalDescription
otherReadonlyCollection<K, T>No
The other Collection to merge with
whenInSelf(value: V, key: K) => Keep<R>No
Function getting the result if the entry only exists in this Collection
whenInOther(valueOther: T, key: K) => Keep<R>No
Function getting the result if the entry only exists in the other Collection
whenInBoth(value: V, valueOther: T, key: K) => Keep<R>No
Function 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);
const [big, small] = collection.partition(guild => guild.memberCount > 250);
NameConstraintsOptionalDefaultDescription
K2KNoNone
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => key is K2No
Function used to test (should return a boolean)
random():V | undefined
Obtains unique random value(s) from this collection.
Returns
A single value if no amount is provided or an array of values
randomKey():K | undefined
Obtains unique random key(s) from this collection.
Returns
A single key if no amount is provided or an array
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);
collection.reduce((acc, guild) => acc + guild.memberCount, 0);
NameConstraintsOptionalDefaultDescription
TYesVNone
NameTypeOptionalDescription
fn(accumulator: T, value: V, key: K, collection: this) => TNo
Function used to reduce, taking four arguments; accumulator, currentValue, currentKey, and collection
initialValueTYes
Starting 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');
collection.some(user => user.discriminator === '0000');
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => unknownNo
Function 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);
collection.sort((userA, userB) => userA.createdTimestamp - userB.createdTimestamp);
NameTypeOptionalDescription
compareFunctionComparator<K, V>Yes
Specifies 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);
collection.sorted((userA, userB) => userA.createdTimestamp - userB.createdTimestamp);
NameTypeOptionalDescription
compareFunctionComparator<K, V>Yes
Specifies 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.
subtract(other):Collection<K, V>
The subtract method returns a new structure containing items where the keys and values of the original structure are not present in the other.
NameConstraintsOptionalDefaultDescription
TNoNone
NameTypeOptionalDescription
otherReadonlyCollection<K, T>No
The other Collection to filter against
sweep(fn):number
Removes items that satisfy the provided filter function.
Returns
The number of removed entries
NameTypeOptionalDescription
fn(value: V, key: K, collection: this) => unknownNo
Function 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))
collection
.tap(coll => console.log(coll.size))
.filter(user => user.bot)
.tap(coll => console.log(coll.size))
NameTypeOptionalDescription
fn(collection: this) => voidNo
Function to execute
toJSON():V[]