Convert an array of objects to a single object

JavaScript

const toObject = (arr, key) => arr.reduce((a, b) => ({ ...a, [b[key]]: b }), {})

// Or
const toObject = (arr, key) => Object.fromEntries(arr.map((it) => [it[key], it]))

TypeScript

const toObject = <T extends Record<string, any>, K extends keyof T>(arr: T[], key: K): Record<string, T> => (
  arr.reduce((a, b) => ({ ...a, [b[key]]: b }), {})
)

const toObject = <T extends Record<string, any>, K extends keyof T>(arr: T[], key: K): Record<string, T> => (
  Object.fromEntries(arr.map((it) => [it[key], it]))
)

Example

toObject([
  { id: '1', name: 'Alpha', gender: 'Male' },
  { id: '2', name: 'Bravo', gender: 'Male' },
  { id: '3', name: 'Charlie', gender: 'Female' }],

  'id'
)

/*
{
  '1': { id: '1', name: 'Alpha', gender: 'Male' },
  '2': { id: '2', name: 'Bravo', gender: 'Male' },
  '3': { id: '3', name: 'Charlie', gender: 'Female' },
}
*/