@geraintguan/ts-std-lib
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    Function groupByUnique

    • Groups elements of an array by a key derived from each element, keeping only the last occurrence of each key.

      Type Parameters

      • T
      • K extends PropertyKey

      Parameters

      • array: T[]

        The array of elements to group.

      • keyFn: (value: T) => K

        A function that takes each element and returns the key to group by.

      Returns Record<K, T>

      An object where each key is derived from the key function and each value is the corresponding (last) element from the array.

      This function is useful when you want to group elements by a key but you know that each element can only appear once per key, or when you only care about the most recent value for each key.

      Unlike a traditional groupBy() function which returns an array of values for each key, this function returns a single value per key. If multiple elements produce the same key, only the latest (last) element in the array will be retained.

      const users = [
        { id: 1, name: "Alice" },
        { id: 2, name: "Bob" },
        { id: 3, name: "Charlie" },
      ];

      groupByUnique(users, (user) => user.id);
      // => {
      //   1: { id: 1, name: "Alice" },
      //   2: { id: 2, name: "Bob" },
      //   3: { id: 3, name: "Charlie" },
      // }

      // When there are duplicate keys, the last value wins
      const items = [
        { key: "a", value: 1 },
        { key: "b", value: 2 },
        { key: "a", value: 3 },
      ];

      groupByUnique(items, (item) => item.key);
      // => {
      //   a: { key: "a", value: 3 },
      //   b: { key: "b", value: 2 },
      // }

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