CFP - Docs

get

(key: PropertyKey) => (anything: any) => any

Return the value found at key

Try It

const getA = get('a')
getA({ a: 'b' }) // is 'b'
getA({}) // is undefined

const getFirst = get(0)
getFirst(['a']) // is 'a'
const getA = get('a')
getA({ a: 'b' }) // is 'b'
getA({}) // is undefined

const getFirst = get(0)
getFirst(['a']) // is 'a'

Try It

const getA = get('a')
getA({ a: 'b' }) // is 'b'
getA({}) // is undefined

const getFirst = get(0)
getFirst(['a']) // is 'a'
const getA = get('a')
getA({ a: 'b' }) // is 'b'
getA({}) // is undefined

const getFirst = get(0)
getFirst(['a']) // is 'a'

Sometimes we need a property's value. Below, we're organizing a conference. We have a list of attendees and are printing pins of everyone's first name. Let's get a list of first names.

Try It

const attendees = [
  { first: 'liz', last: 'brown' },
  { first: 'phil', last: 'smith' },
  { first: 'mary', last: 'garcia' },
]

const getFirstName = get('first')
const getAllFirstNames = mapValues(getFirstName)
const firstNames = getAllFirstNames(attendees)
console.log(firstNames)
// is [
//   liz,
//   phil,
//   mary,
// ]
type Person = { first: string; last: string }

const attendees: Person[] = [
  { first: 'liz', last: 'brown' },
  { first: 'phil', last: 'smith' },
  { first: 'mary', last: 'garcia' },
]

const getFirstName = get('first')<Person>
const getAllFirstNames = mapValues(getFirstName)<Person[]>
const firstNames = getAllFirstNames(attendees)
console.log(firstNames)
// is [
//   liz,
//   phil,
//   mary,
// ]

Try It

const attendees = [
  { first: 'liz', last: 'brown' },
  { first: 'phil', last: 'smith' },
  { first: 'mary', last: 'garcia' },
]

const getFirstName = get('first')
const getAllFirstNames = mapValues(getFirstName)
const firstNames = getAllFirstNames(attendees)
console.log(firstNames)
// is [
//   liz,
//   phil,
//   mary,
// ]
type Person = { first: string; last: string }

const attendees: Person[] = [
  { first: 'liz', last: 'brown' },
  { first: 'phil', last: 'smith' },
  { first: 'mary', last: 'garcia' },
]

const getFirstName = get('first')<Person>
const getAllFirstNames = mapValues(getFirstName)<
  Person[]
>
const firstNames = getAllFirstNames(attendees)
console.log(firstNames)
// is [
//   liz,
//   phil,
//   mary,
// ]

This utility does not treat Maps differently. It only gets object properties. If you're looking to get the value out of a map, use getValueAtMapKey.