CFP - Docs - findKeyWithVal

findKeyWithVal

(value: any) => (collection: EntryCollection | string) => Key

Find the first key or index of collection which has value.

Try It

const findKeyOf2 = findKeyWithVal(2)
const findKeyOfB = findKeyWithVal('b')

findKeyOf2([1, 2, 3]) // is 1
findKeyOf2([1, 2, 3, 2]) // is 1
findKeyOf2([1, 3, 4]) // is undefined

findKeyOf2({ a: 1, b: 2 }) // is 'b'
findKeyOfB('ab') // is 1
const findKeyOf2 = findKeyWithVal(2)
const findKeyOfB = findKeyWithVal('b')

findKeyOf2([1, 2, 3]) // is 1
findKeyOf2([1, 2, 3, 2]) // is 1
findKeyOf2([1, 3, 4]) // is undefined

findKeyOf2({ a: 1, b: 2 }) // is 'b'
findKeyOfB('ab') // is 1

Try It

const findKeyOf2 = findKeyWithVal(2)
const findKeyOfB = findKeyWithVal('b')

findKeyOf2([1, 2, 3]) // is 1
findKeyOf2([1, 2, 3, 2]) // is 1
findKeyOf2([1, 3, 4]) // is undefined

findKeyOf2({ a: 1, b: 2 }) // is 'b'
findKeyOfB('ab') // is 1
const findKeyOf2 = findKeyWithVal(2)
const findKeyOfB = findKeyWithVal('b')

findKeyOf2([1, 2, 3]) // is 1
findKeyOf2([1, 2, 3, 2]) // is 1
findKeyOf2([1, 3, 4]) // is undefined

findKeyOf2({ a: 1, b: 2 }) // is 'b'
findKeyOfB('ab') // is 1

Sometimes we want to find the key to a value. Below, we have a raffle. Let's find the winner.

Try It

const ticketHolders = {
  mike: 152876,
  luke: 961273,
  emma: 428670,
}

const winningTicket = 961273
const findWinner = findKeyWithVal(winningTicket)
const winner = findWinner(ticketHolders)

console.log(winner)
// is luke
type TicketHolders = Record<string, number>
const ticketHolders: TicketHolders = {
  mike: 152876,
  luke: 961273,
  emma: 428670,
}

const winningTicket = 961273
const findWinner = findKeyWithVal(winningTicket)<TicketHolders>
const winner = findWinner(ticketHolders)

console.log(winner)
// is luke

Try It

const ticketHolders = {
  mike: 152876,
  luke: 961273,
  emma: 428670,
}

const winningTicket = 961273
const findWinner = findKeyWithVal(winningTicket)
const winner = findWinner(ticketHolders)

console.log(winner)
// is luke
type TicketHolders = Record<string, number>
const ticketHolders: TicketHolders = {
  mike: 152876,
  luke: 961273,
  emma: 428670,
}

const winningTicket = 961273
const findWinner = findKeyWithVal(
  winningTicket
)<TicketHolders>
const winner = findWinner(ticketHolders)

console.log(winner)
// is luke