Collection

Represents a collection that extends the built-in Map class.

Extends

• Map<K, V>

Type parameters

Type parameter	Description
K	The type of the keys in the collection.
V	The type of the values in the collection.

Constructors

new Collection(entries)

new Collection<K, V>(entries?: null | readonly readonly [K, V][]): Collection<K, V>

Parameters

Parameter	Type
entries?	null | readonly readonly [K, V][]

Returns

Collection<K, V>

Inherited from

Map<K, V>.constructor

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:50

new Collection(iterable)

new Collection<K, V>(iterable?: null | Iterable<readonly [K, V]>): Collection<K, V>

Parameters

Parameter	Type
iterable?	null | Iterable<readonly [K, V]>

Returns

Collection<K, V>

Inherited from

Map<K, V>.constructor

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:49

Properties

Property	Modifier	Type	Description	Inherited from
[toStringTag]	readonly	string	-	Map.[toStringTag]
size	readonly	number		Map.size
[species]	readonly	MapConstructor	-	Map.[species]

Methods

[iterator]()

iterator: IterableIterator<[K, V]>

Returns an iterable of entries in the map.

Returns

IterableIterator<[K, V]>

Inherited from

Map.[iterator]

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.iterable.d.ts:119

---

clear()

clear(): void

Returns

void

Inherited from

Map.clear

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:20

---

delete()

delete(key: K): boolean

Parameters

Parameter	Type
key	K

Returns

boolean

true if an element in the Map existed and has been removed, or false if the element does not exist.

Inherited from

Map.delete

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:24

---

entries()

entries(): IterableIterator<[K, V]>

Returns an iterable of key, value pairs for every entry in the map.

Returns

IterableIterator<[K, V]>

Inherited from

Map.entries

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.iterable.d.ts:124

---

every()

every(fn:     (value: V, key: K, collection: this) => boolean): boolean

Checks if all elements in the collection pass a test implemented by the provided function.

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => boolean	The function to test each element of the collection.

Returns

boolean

true if all elements pass the test, otherwise false.

Example

const collection = new Collection<number, number>();
collection.set(1, 1);
collection.set(2, 2);
collection.set(3, 3);
const allGreaterThanZero = collection.every(value => value > 0);
console.log(allGreaterThanZero); // Output: true

Source

seyfert/src/collection.ts:120

---

filter()

filter(fn:     (value: V, key: K, collection: this) => boolean): V[]

Creates a new array with all elements that pass the test implemented by the provided function.

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => boolean	The function to test each element of the collection.

Returns

V[]

A new array with the elements that pass the test.

Example

const collection = new Collection<number, string>();
collection.set(1, 'one');
collection.set(2, 'two');
collection.set(3, 'three');
const filteredArray = collection.filter((value, key) => key % 2 === 0);
console.log(filteredArray); // Output: ['two']

Source

seyfert/src/collection.ts:67

---

find()

find(fn:     (value: V, key: K, collection: this) => boolean): undefined | V

Returns the value of the first element in the collection that satisfies the provided testing function.

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => boolean	The function to test each element of the collection.

Returns

undefined | V

The value of the first element that passes the test. undefined if no element passes the test.

Example

const collection = new Collection<number, number>();
collection.set(1, 1);
collection.set(2, 2);
collection.set(3, 3);
const firstEvenValue = collection.find(value => value % 2 === 0);
console.log(firstEvenValue); // Output: 2

Source

seyfert/src/collection.ts:164

---

findKey()

findKey(fn:     (value: V, key: K, collection: this) => boolean): undefined | K

Returns the first key in the collection that satisfies the provided testing function.

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => boolean	The function to test each element of the collection.

Returns

undefined | K

The first key that passes the test. undefined if no element passes the test.

Example

const collection = new Collection<number, number>();
collection.set(1, 1);
collection.set(2, 2);
collection.set(3, 3);
const firstEvenKey = collection.findKey(value => value % 2 === 0);
console.log(firstEvenKey); // Output: 2

Source

seyfert/src/collection.ts:185

---

forEach()

forEach(callbackfn:     (value: V, key: K, map: Map<K, V>) => void, thisArg?: any): void

Executes a provided function once per each key/value pair in the Map, in insertion order.

Parameters

Parameter	Type
callbackfn	(value: V, key: K, map: Map<K, V>) => void
thisArg?	any

Returns

void

Inherited from

Map.forEach

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:28

---

get()

get(key: K): undefined | V

Returns a specified element from the Map object. If the value that is associated to the provided key is an object, then you will get a reference to that object and any change made to that object will effectively modify it inside the Map.

Parameters

Parameter	Type
key	K

Returns

undefined | V

Returns the element associated with the specified key. If no element is associated with the specified key, undefined is returned.

Inherited from

Map.get

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:33

---

has()

has(key: K): boolean

Parameters

Parameter	Type
key	K

Returns

boolean

boolean indicating whether an element with the specified key exists or not.

Inherited from

Map.has

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:37

---

keys()

keys(): IterableIterator<K>

Returns an iterable of keys in the map

Returns

IterableIterator<K>

Inherited from

Map.keys

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.iterable.d.ts:129

---

map()

map<T>(fn:     (value: V, key: K, collection: this) => T): T[]

Creates a new array with the results of calling a provided function on every element in the collection.

Type parameters

Type parameter	Value
T	any

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => T	The function that produces an element of the new array.

Returns

T[]

A new array with the results of calling the provided function on every element in the collection.

Example

const collection = new Collection<number, string>();
collection.set(1, 'one');
collection.set(2, 'two');
collection.set(3, 'three');
const mappedArray = collection.map((value, key) => `${key}: ${value}`);
console.log(mappedArray); // Output: ['1: one', '2: two', '3: three']

Source

seyfert/src/collection.ts:44

---

reduce()

reduce<T>(fn:     (accumulator: T, value: V, key: K, collection: this) => T, initialValue?: T): T

Apply a function against an accumulator and each element in the collection (from left to right) to reduce it to a single value.

Type parameters

Type parameter	Value
T	any

Parameters

Parameter	Type	Description
fn	(accumulator: T, value: V, key: K, collection: this) => T	The function to execute on each element in the collection.
initialValue?	T	The initial value of the accumulator.

Returns

T

The value that results from the reduction.

Example

const collection = new Collection<number, number>();
collection.set(1, 1);
collection.set(2, 2);
collection.set(3, 3);
const sum = collection.reduce((acc, value) => acc + value, 0);
console.log(sum); // Output: 6

Source

seyfert/src/collection.ts:90

---

set()

set(key: K, value: V): this

Adds a new element with a specified key and value to the Map. If an element with the same key already exists, the element will be updated.

Parameters

Parameter	Type
key	K
value	V

Returns

this

Inherited from

Map.set

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.collection.d.ts:41

---

some()

some(fn:     (value: V, key: K, collection: this) => boolean): boolean

Checks if at least one element in the collection passes a test implemented by the provided function.

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => boolean	The function to test each element of the collection.

Returns

boolean

true if at least one element passes the test, otherwise false.

Example

const collection = new Collection<number, number>();
collection.set(1, 1);
collection.set(2, 2);
collection.set(3, 3);
const hasEvenValue = collection.some(value => value % 2 === 0);
console.log(hasEvenValue); // Output: true

Source

seyfert/src/collection.ts:142

---

sweep()

sweep(fn:     (value: V, key: K, collection: this) => unknown): number

Removes elements from the collection based on a filter function.

Parameters

Parameter	Type	Description
fn	(value: V, key: K, collection: this) => unknown	The filter function that determines which elements to remove.

Returns

number

The number of elements removed from the collection.

Example

const collection = new Collection<number, string>();
collection.set(1, 'one');
collection.set(2, 'two');
collection.set(3, 'three');
const removedCount = collection.sweep((value, key) => key % 2 === 0);
console.log(removedCount); // Output: 1
console.log(collection.size); // Output: 2

Source

seyfert/src/collection.ts:23

---

values()

values(): IterableIterator<V>

Returns an iterable of values in the map

Returns

IterableIterator<V>

Inherited from

Map.values

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.es2015.iterable.d.ts:134

---

groupBy()

static groupBy<K, T>(items: Iterable<T>, keySelector:     (item: T, index: number) => K): Map<K, T[]>

Groups members of an iterable according to the return value of the passed callback.

Type parameters

Type parameter
K
T

Parameters

Parameter	Type	Description
items	Iterable<T>	An iterable.
keySelector	(item: T, index: number) => K	A callback which will be invoked for each item in items.

Returns

Map<K, T[]>

Inherited from

Map.groupBy

Source

node_modules/.pnpm/typescript@5.4.5/node_modules/typescript/lib/lib.esnext.collection.d.ts:25