[Feature]: How about add `indexBy` function

Package Scope

• Add to an existing package
• New package

Package name: @toss/utils

Overview

A function that indexes an array of objects based on a specific key value. It is a function that makes the object a key and value pair , which makes the cost of find specific data in the future cheaper.

const foo = [
  { id: 1, name: 'park', age: 23 },
  { id: 3, name: 'kim', age: 21 },
  { id: 5, name: 'lee', age: 24 },
];

// normal approach
const result = foo.find(item => item.name === "park") // Tour all items.
const result = foo.find(item => item.name === "kim") // Tour all items.
const result = foo.find(item => item.name === "lee") // Tour all items.

// new indexBy function

const indexedObj = indexBy(foo, "name") // Tour just one tiem
const result = indexedObj["kim"] // quick search
const result = indexedObj["lee"] // quick search
const result = indexedObj["park"] // quick search

If indexed, it is a performance-friendly situation because it can be found immediately without looking for values while traveling all list. These functions are good for those situations when they can be found quickly and easily after a just one traveling.

Describe the solution you’d like

type ElementType<T extends unknown[]> = T[number];

const indexBy = <ArrayObjectType extends Array<Record<PropertyKey, unknown>>, IndexType extends keyof ElementType<ArrayObjectType>>(
  arrayObj:ArrayObjectType, key:IndexType
) => {

  return arrayObj.reduce((acc, obj) => {
    acc[obj[key]] = obj;
     return acc
     }, {} as any);
}

Additional context

If the developer uses a key which have value that is other than a Property Key, it should be treated well.

[raon0211]

There is actually an identical utility function in @toss/utils, namely createMapByKey.

[HoseungJang]

I think we can just use Map or Set, not the new util.

const foo = [
  { id: 1, name: 'park', age: 23 },
  { id: 3, name: 'kim', age: 21 },
  { id: 5, name: 'lee', age: 24 },
];

const names = new Set(foo.map(({ name }) => name));

if (name.has('park')) {
  ...
}

const fooByName = new Map(foo.map((e) => [e.name, e]));

const result = fooByName.get('park');