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    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?: number): 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]"(): MapIterator<[K, number]>

      Returns an iterable of entries in the map.

      Returns MapIterator<[K, number]>

    add

    • add(key: K, amount?: number): number

      Parameters

      • key: K
      • amount: number = 1

      Returns number

    clear

    • clear(): void

      Returns void

    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.

    entries

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

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

      Returns MapIterator<[K, number]>

    forEach

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

      Returns void

    get

    • get(key: K): 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: K): boolean

      Parameters

      • key: K

      Returns boolean

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

    keys

    • keys(): MapIterator<K>

      Returns an iterable of keys in the map

      Returns MapIterator<K>

    multiply

    • multiply(key: K, amount: number): number

      Parameters

      • key: K
      • amount: number

      Returns number

    reset

    • reset(key: K): number

      Parameters

      • key: K

      Returns number

    set

    • set(key: K, value: number): 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: K, amount?: number): number

      Parameters

      • key: K
      • amount: number = 1

      Returns number

    values

    • values(): MapIterator<number>

      Returns an iterable of values in the map

      Returns MapIterator<number>

    StaticgroupBy

    • 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[]>

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