CFP - Docs - isFalsey

isFalsey

```
(value: any) => boolean
```

Test whether a value is falsey

isFalsey(undefined) // is true
isFalsey('') // is true
isFalsey(0) // is true

isFalsey('a') // is false
isFalsey(1) // is false
isFalsey(undefined) // is true
isFalsey('') // is true
isFalsey(0) // is true

isFalsey('a') // is false
isFalsey(1) // is false

Try It

isFalsey(undefined) // is true
isFalsey('') // is true
isFalsey(0) // is true

isFalsey('a') // is false
isFalsey(1) // is false
isFalsey(undefined) // is true
isFalsey('') // is true
isFalsey(0) // is true

isFalsey('a') // is false
isFalsey(1) // is false

Sometimes falsey values need to be handled. Below, we have applicants compiled from multiple sources. If a field is falsey, that means the data is missing. Let's get the missing fields so we can reach back out to the applicants.

Try It

const applicants = {
  chris: {
    yearsExperience: undefined,
    applied: '2025 02 15',
  },
  liz: {
    yearsExperience: '2',
    applied: '',
  },
}

const getMissingFields = compose([keepWhen(isFalsey), Object.keys])
const getAllMissingFields = mapValues(getMissingFields)
const applicantPrompts = getAllMissingFields(applicants)
console.log(applicantPrompts)
// is {
//   chris: [yearsExperience]
//   liz: [applied]
// }
type Applicant = {
  yearsExperience?: string
  applied?: string
}
type Applicants = Record<string, Applicant>
const applicants: Applicants = {
  chris: {
    yearsExperience: undefined,
    applied: '2025 02 15',
  },
  liz: {
    yearsExperience: '2',
    applied: '',
  },
}

const getMissingFields = compose([keepWhen(isFalsey)<Applicant>, Object.keys])
const getAllMissingFields = mapValues(getMissingFields)<Applicants>
const applicantPrompts = getAllMissingFields(applicants)
console.log(applicantPrompts)
// is {
//   chris: [yearsExperience]
//   liz: [applied]
// }

Try It

const applicants = {
  chris: {
    yearsExperience: undefined,
    applied: '2025 02 15',
  },
  liz: {
    yearsExperience: '2',
    applied: '',
  },
}

const getMissingFields = compose([
  keepWhen(isFalsey),
  Object.keys,
])
const getAllMissingFields = mapValues(
  getMissingFields
)
const applicantPrompts =
  getAllMissingFields(applicants)
console.log(applicantPrompts)
// is {
//   chris: [yearsExperience]
//   liz: [applied]
// }
type Applicant = {
  yearsExperience?: string
  applied?: string
}
type Applicants = Record<string, Applicant>
const applicants: Applicants = {
  chris: {
    yearsExperience: undefined,
    applied: '2025 02 15',
  },
  liz: {
    yearsExperience: '2',
    applied: '',
  },
}

const getMissingFields = compose([
  keepWhen(isFalsey)<Applicant>,
  Object.keys,
])
const getAllMissingFields = mapValues(
  getMissingFields
)<Applicants>
const applicantPrompts =
  getAllMissingFields(applicants)
console.log(applicantPrompts)
// is {
//   chris: [yearsExperience]
//   liz: [applied]
// }