khrulenko / ts_group_by_key Goto Github PK

This is a similar task from the course of JS Advanced, but now it is strictly typed and uses generic types. You need to aggregate data based on a particular key, for instance, by the author of the book.

1. You are given an interface Item, which has index key of type string and values of type any.

interface Item {
  [key: string]: any
}

2. You are given a generic interface ItemsGroup, which has index key of type string and values of type array of T.

interface ItemsGroup<T> {
  [key: string]: T[]
}

3. Your task is to implement function groupByKey, which takes two arguments: array of T objects and string key. The function should read key of each object in the array and group them into ItemsGroup.

Hint: You should use a new keyword in types definition called keyof for correct TypeScript type checks.