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    Interface IMapImmutable<K, V>

    An immutable map. Rather than changing the map, functions like add and delete return a new map reference which must be captured.

    Immutable data is useful because as it gets passed around your code, it never changes from underneath you. You have what you have.

    Example

    let m = map(); // Create
    let m2 = m.set(`hello`, `samantha`);
    // m is still empty, only m2 contains a value.
    interface IMapImmutable<K, V> {
        add(...itemsToAdd: EitherKey<K, V>): IMapImmutable<K, V>;
        clear(): IMapImmutable<K, V>;
        delete(key: K): IMapImmutable<K, V>;
        entries(): IterableIterator<readonly [K, V]>;
        get(key: K): undefined | V;
        has(key: K): boolean;
        isEmpty(): boolean;
        set(key: K, value: V): IMapImmutable<K, V>;
        values(): IterableIterator<V>;
    }

    Type Parameters

    • K

      Type of map keys. Typically string

    • V

      Type of stored values

    Hierarchy

    • IMapBase<K, V>
      • IMapImmutable

    Methods

    add clear delete entries get has isEmpty set values

    Methods

    add

    • add(...itemsToAdd: EitherKey<K, V>): IMapImmutable<K, V>

      Adds one or more items, returning the changed map.

      Can add items in the form of [key,value] or {key, value}.

      Parameters

      Returns IMapImmutable<K, V>

      Example: These all produce the same result

      map.set(`hello`, `samantha`);
      map.add([`hello`, `samantha`]);
      map.add({key: `hello`, value: `samantha`})

    clear

    delete

    entries

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

      Iterates over entries (consisting of [key,value])

      Returns IterableIterator<readonly [K, V]>

      Example

      for (const [key, value] of map.entries()) {
       // Use key, value...
      }

    get

    • get(key: K): undefined | V

      Gets an item by key

      Parameters

      • key: K

      Returns undefined | V

      Example

      const item = map.get(`hello`);

    has

    • has(key: K): boolean

      Returns true if map contains key

      Parameters

      • key: K

      Returns boolean

      Example

      if (map.has(`hello`)) ...

    isEmpty

    • isEmpty(): boolean

      Returns true if map is empty

      Returns boolean

    set

    • set(key: K, value: V): IMapImmutable<K, V>

      Sets key to be value, overwriting anything existing. Returns a new map with added key.

      Parameters

      • key: K
      • value: V

      Returns IMapImmutable<K, V>

    values

    • values(): IterableIterator<V>

      Returns IterableIterator<V>

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