Class DefaultMap<K, V, D>

A Map that has a default value for missing keys.

Example

const map = new DefaultMap(0);

map.get('a'); // 0

Example

const map = new DefaultMap(key => key.toUpperCase());

map.get('a'); // 'A'

Map

Type Parameters

K
V
D extends V = V

Hierarchy (View Summary)

Map<K, V>
- DefaultMap
  - MathMap

Index

Constructors

constructor

new DefaultMap<K, V, D = V>(
defaultValue: Exclude<D, AnyFunction>,
entries?: Iterable<readonly [unknown, unknown], any, any> | null,
): DefaultMap<K, V, D>
Create a new DefaultMap with a specified default value.

Time complexity: O(n)

Space complexity: O(n)
Type Parameters
- K
- V
- D = V
Parameters
- defaultValue: Exclude<D, AnyFunction>
  The default value to use for missing keys
- Optionalentries: Iterable<readonly [unknown, unknown], any, any> | null
Returns DefaultMap<K, V, D>
Example
```
const map = new DefaultMap(0);
```
Overrides Map<K, V>.constructor
- Defined in src/map/default-map.ts:39
new DefaultMap<K, V, D = V>(
defaultValueFunction: (key: K) => D,
entries?: Iterable<readonly [unknown, unknown], any, any> | null,
): DefaultMap<K, V, D>
Create a new DefaultMap with a specified function to generate default values.

Time complexity: O(n)

Space complexity: O(n)
Type Parameters
- K
- V
- D = V
Parameters
- defaultValueFunction: (key: K) => D
- Optionalentries: Iterable<readonly [unknown, unknown], any, any> | null
Returns DefaultMap<K, V, D>
Example
```
const map = new DefaultMap(key => key.toUpperCase());
```
Overrides Map<K, V>.constructor
- Defined in src/map/default-map.ts:54

Properties

`Readonly`[toStringTag]

"[toStringTag]": string

`Readonly`size

size: number

Returns

the number of elements in the Map.

`Static` `Readonly`[species]

"[species]": MapConstructor

Methods

[iterator]

"[iterator]"(): MapIterator<[K, V]>
Returns an iterable of entries in the map.

Returns MapIterator<[K, V]>
Inherited from Map.[iterator]
- Defined in node_modules/typescript/lib/lib.es2015.iterable.d.ts:143

clear

clear(): void
Returns void
Inherited from Map.clear
- Defined in node_modules/typescript/lib/lib.es2015.collection.d.ts:20

delete

delete(key: K): boolean
Parameters
- 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
- Defined in node_modules/typescript/lib/lib.es2015.collection.d.ts:24

entries

entries(): MapIterator<[K, V]>
Returns an iterable of key, value pairs for every entry in the map.

Returns MapIterator<[K, V]>
Inherited from Map.entries
- Defined in node_modules/typescript/lib/lib.es2015.iterable.d.ts:148

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
- callbackfn: (value: V, key: K, map: Map<K, V>) => void
- OptionalthisArg: any
Returns void
Inherited from Map.forEach
- Defined in node_modules/typescript/lib/lib.es2015.collection.d.ts:28

get

get(key: K): V | D
Get the value for a given key, or the default value if it's missing.

Time complexity: O(1)

Space complexity: O(1)
Parameters
- key: K
  The key to get the value for
Returns V | D
The value for key, or the default value if it's missing
Example
```
map.get('a');
```
Overrides Map.get
- Defined in src/map/default-map.ts:79

has

has(key: K): boolean
Parameters
- key: K
Returns boolean
boolean indicating whether an element with the specified key exists or not.
Inherited from Map.has
- Defined in node_modules/typescript/lib/lib.es2015.collection.d.ts:37

keys

keys(): MapIterator<K>
Returns an iterable of keys in the map

Returns MapIterator<K>
Inherited from Map.keys
- Defined in node_modules/typescript/lib/lib.es2015.iterable.d.ts:153

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
- key: K
- value: V
Returns this
Inherited from Map.set
- Defined in node_modules/typescript/lib/lib.es2015.collection.d.ts:41

values

values(): MapIterator<V>
Returns an iterable of values in the map

Returns MapIterator<V>
Inherited from Map.values
- Defined in node_modules/typescript/lib/lib.es2015.iterable.d.ts:158

`Static`groupBy

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
- K
- T
Parameters
- 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
- Defined in node_modules/typescript/lib/lib.es2024.collection.d.ts:25

Class DefaultMap<K, V, D>

Example

Example

Type Parameters

Hierarchy (View Summary)

Index

Constructors

Properties

Methods

Constructors

constructor

Type Parameters

Parameters

Returns DefaultMap<K, V, D>

Example

Type Parameters

Parameters

Returns DefaultMap<K, V, D>

Example

Properties

Readonly[toStringTag]

Readonlysize

Returns

Static Readonly[species]

Methods

[iterator]

Returns MapIterator<[K, V]>

clear

Returns void

delete

Parameters

Returns boolean

entries

Returns MapIterator<[K, V]>

forEach

Parameters

Returns void

get

Parameters

Returns V | D

Example

has

Parameters

Returns boolean

keys

Returns MapIterator<K>

set

Parameters

Returns this

values

Returns MapIterator<V>

StaticgroupBy

Type Parameters

Parameters

Returns Map<K, T[]>

Settings

On This Page

`Readonly`[toStringTag]

`Readonly`size

`Static` `Readonly`[species]

`Static`groupBy