CFP - Docs - find

find

(predicate: Predicate) => (collection: Collection) => Value | undefined

Find the first value which passes a condition.

Try It

const gt1 = n => n > 1
const findGt1 = find(gt1)

findGt1([1, 2, 3]) // is 2
findGt1([0, 1]) // is undefined
findGt1({ a: 1, b: 2, c: 3 }) // is 2
const gt1 = (n: number) => n > 1
const findGt1 = find(gt1)

findGt1([1, 2, 3]) // is 2
findGt1([0, 1]) // is undefined
findGt1({ a: 1, b: 2, c: 3 }) // is 2

Try It

const gt1 = n => n > 1
const findGt1 = find(gt1)

findGt1([1, 2, 3]) // is 2
findGt1([0, 1]) // is undefined
findGt1({ a: 1, b: 2, c: 3 }) // is 2
const gt1 = (n: number) => n > 1
const findGt1 = find(gt1)

findGt1([1, 2, 3]) // is 2
findGt1([0, 1]) // is undefined
findGt1({ a: 1, b: 2, c: 3 }) // is 2

Sometimes we want to find a value that passes a condition. Below, we want to find our neighbor Tom's number to invite him for some barbecue.

Try It

const directory = {
  101: { name: 'meg', phone: '555-1873' },
  102: { name: 'tom', phone: '555-7692' },
  103: { name: 'ken', phone: '555-4405' },
}

const findTom = find(resident => resident.name === 'tom')
const tom = findTom(directory)
console.log(tom.phone)
// is 555-7692
type Resident = {
  name: string
  phone: string
}
type Directory = Record<number, Resident>
const directory: Directory = {
  101: { name: 'meg', phone: '555-1873' },
  102: { name: 'tom', phone: '555-7692' },
  103: { name: 'ken', phone: '555-4405' },
}

const findTom = find((resident: Resident) => resident.name === 'tom')<Directory>
const tom = findTom(directory) as Resident
console.log(tom.phone)
// is 555-7692

Try It

const directory = {
  101: { name: 'meg', phone: '555-1873' },
  102: { name: 'tom', phone: '555-7692' },
  103: { name: 'ken', phone: '555-4405' },
}

const findTom = find(
  resident => resident.name === 'tom'
)
const tom = findTom(directory)
console.log(tom.phone)
// is 555-7692
type Resident = {
  name: string
  phone: string
}
type Directory = Record<number, Resident>
const directory: Directory = {
  101: { name: 'meg', phone: '555-1873' },
  102: { name: 'tom', phone: '555-7692' },
  103: { name: 'ken', phone: '555-4405' },
}

const findTom = find(
  (resident: Resident) => resident.name === 'tom'
)<Directory>
const tom = findTom(directory) as Resident
console.log(tom.phone)
// is 555-7692