CFP - Docs - mAssignDefaults

mAssignDefaults

(defaults: object) => (base: object) => base

(defaults: map) => (base: map) => base

Assign a over defaults.

Consider assignDefaults instead.
This is for the uncommon case where mutating base is required.

Try It

const ab = { a: 1, b: 2 }
const assignDefaultsAB = mAssignDefaults(ab)
const obj = { a: 2, c: 3 }
const mutatedObj = assignDefaultsAB(obj)

console.log(mutatedObj === obj) // is true
console.log(obj) // is { a: 2, c: 3, b: 2 }
type ABC = {
  a: number
  b: number
  c: number
}

const ab = { a: 1, b: 2 }
const assignDefaultsAB = mAssignDefaults(ab)
const obj = { a: 2, c: 3 } as ABC
const mutatedObj = assignDefaultsAB(obj)

console.log(mutatedObj === obj) // is true
console.log(obj) // is { a: 2, c: 3, b: 2 }

Try It

const ab = { a: 1, b: 2 }
const assignDefaultsAB = mAssignDefaults(ab)
const obj = { a: 2, c: 3 }
const mutatedObj = assignDefaultsAB(obj)

console.log(mutatedObj === obj) // is true
console.log(obj) // is { a: 2, c: 3, b: 2 }
type ABC = {
  a: number
  b: number
  c: number
}

const ab = { a: 1, b: 2 }
const assignDefaultsAB = mAssignDefaults(ab)
const obj = { a: 2, c: 3 } as ABC
const mutatedObj = assignDefaultsAB(obj)

console.log(mutatedObj === obj) // is true
console.log(obj) // is { a: 2, c: 3, b: 2 }

Sometimes we want to mutate a collection by assigning defaults. Below, we have a list of wedding dinner orders. By default they're served chicken and rice, but they can choose tofu or a salad. Let's get the final orders for the wedding.

Try It

const defaultDinner = {
  side: 'rice',
  main: 'chicken',
}

const orders = {
  emma: {
    side: 'salad',
    main: 'tofu',
  },
  meg: {
    side: 'salad',
  },
  tom: {},
}

const assignDefaultDinner = mAssignDefaults(defaultDinner)
const assignDinners = forEach(assignDefaultDinner)
assignDinners(orders)
console.log(orders)
// is {
//   emma: {
//     side: salad
//     main: tofu
//   }
//   meg: {
//     side: salad
//     main: chicken
//   }
//   tom: {
//     side: rice
//     main: chicken
//   }
// }
type Dinner = {
  side: 'rice' | 'salad'
  main: 'chicken' | 'tofu'
}

const defaultDinner: Dinner = {
  side: 'rice',
  main: 'chicken',
}

type Orders = Record<string, Dinner>
const orders: Orders = {
  emma: {
    side: 'salad',
    main: 'tofu',
  },
  meg: {
    side: 'salad',
  } as Dinner,
  tom: {} as Dinner,
}

const assignDefaultDinner = mAssignDefaults(defaultDinner)
const assignDinners = forEach(assignDefaultDinner)<Orders>
assignDinners(orders)
console.log(orders)
// is {
//   emma: {
//     side: salad
//     main: tofu
//   }
//   meg: {
//     side: salad
//     main: chicken
//   }
//   tom: {
//     side: rice
//     main: chicken
//   }
// }

Try It

const defaultDinner = {
  side: 'rice',
  main: 'chicken',
}

const orders = {
  emma: {
    side: 'salad',
    main: 'tofu',
  },
  meg: {
    side: 'salad',
  },
  tom: {},
}

const assignDefaultDinner = mAssignDefaults(
  defaultDinner
)
const assignDinners = forEach(assignDefaultDinner)
assignDinners(orders)
console.log(orders)
// is {
//   emma: {
//     side: salad
//     main: tofu
//   }
//   meg: {
//     side: salad
//     main: chicken
//   }
//   tom: {
//     side: rice
//     main: chicken
//   }
// }
type Dinner = {
  side: 'rice' | 'salad'
  main: 'chicken' | 'tofu'
}

const defaultDinner: Dinner = {
  side: 'rice',
  main: 'chicken',
}

type Orders = Record<string, Dinner>
const orders: Orders = {
  emma: {
    side: 'salad',
    main: 'tofu',
  },
  meg: {
    side: 'salad',
  } as Dinner,
  tom: {} as Dinner,
}

const assignDefaultDinner = mAssignDefaults(
  defaultDinner
)
const assignDinners = forEach(
  assignDefaultDinner
)<Orders>
assignDinners(orders)
console.log(orders)
// is {
//   emma: {
//     side: salad
//     main: tofu
//   }
//   meg: {
//     side: salad
//     main: chicken
//   }
//   tom: {
//     side: rice
//     main: chicken
//   }
// }