Class NumberMap<K>

Simple map for numbers.

Keys not present in map return the defaultValue given in the constructor

// All keys default to zero.
const map = new NumberMap();
map.get(`hello`); // 0

To check if a key is present, use has:

map.has(`hello`); // false

Math:

// Adds 1 by default to value of `hello`
map.add(`hello`);         // 1
map.multiply(`hello`, 2); // 2 

// Reset key to default value
map.reset(`hello`); // 0

Different default value:

const map = new NumberMap(10);
map.get(`hello`); // 10

Regular set works as well:

map.set(`hello`, 5);
map.add(`hello`, 2); // 7

Type Parameters

  • K

Hierarchy

  • Map<K, number>
    • NumberMap

Constructors

constructor

Properties

[toStringTag] defaultValue size [species]

Methods

[iterator] add clear delete entries forEach get has keys multiply reset set subtract values groupBy

Constructors

constructor

  • new NumberMap<K>(defaultValue?): NumberMap<K>

  • Type Parameters

    • K

    Parameters

    • defaultValue: number = 0

    Returns NumberMap<K>

Properties

Readonly[toStringTag]

[toStringTag]: string

ReadonlydefaultValue

defaultValue: number

Readonlysize

size: number

Returns

the number of elements in the Map.

Static Readonly[species]

[species]: MapConstructor

Methods

[iterator]

  • [iterator](): IterableIterator<[K, number]>

  • Returns an iterable of entries in the map.

    Returns IterableIterator<[K, number]>

add

  • add(key, amount?): number

  • Parameters

    • key: K
    • amount: number = 1

    Returns number

clear

  • clear(): void

  • Returns void

delete

  • delete(key): 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.

entries

  • entries(): IterableIterator<[K, number]>

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

    Returns IterableIterator<[K, number]>

forEach

  • forEach(callbackfn, thisArg?): void

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

    Parameters

    • callbackfn: ((value: number, key: K, map: Map<K, number>) => void)
        • (value, key, map): void

        • Parameters

          • value: number
          • key: K
          • map: Map<K, number>

          Returns void

    • OptionalthisArg: any

    Returns void

get

  • get(key): number

  • 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

    • key: K

    Returns number

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

has

  • has(key): boolean

  • Parameters

    • key: K

    Returns boolean

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

keys

  • keys(): IterableIterator<K>

  • Returns an iterable of keys in the map

    Returns IterableIterator<K>

multiply

  • multiply(key, amount): number

  • Parameters

    • key: K
    • amount: number

    Returns number

reset

  • reset(key): number

  • Parameters

    • key: K

    Returns number

set

  • set(key, value): 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: number

    Returns this

subtract

  • subtract(key, amount?): number

  • Parameters

    • key: K
    • amount: number = 1

    Returns number

values

  • values(): IterableIterator<number>

  • Returns an iterable of values in the map

    Returns IterableIterator<number>

StaticgroupBy

  • groupBy<K, T>(items, keySelector): 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.

        • (item, index): K

        • Parameters

          • item: T
          • index: number

          Returns K

    Returns Map<K, T[]>

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