CFP - Docs - assignDefaults

assignDefaults

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

(defaults: map) => (base: map) => map

Assign a KeyedCollection over defaults.

Try It

const ab = { a: 1, b: 2 }
const assignABDefaults = assignDefaults(ab)
const abc = assignABDefaults({ a: 2, c: 3 })
console.log(abc) // is { a: 2, b: 2, c: 3 }
const ab = { a: 1, b: 2 }
const assignABDefaults = assignDefaults(ab)
const abc = assignABDefaults({ a: 2, c: 3 })
console.log(abc) // is { a: 2, b: 2, c: 3 }

Try It

const ab = { a: 1, b: 2 }
const assignABDefaults = assignDefaults(ab)
const abc = assignABDefaults({ a: 2, c: 3 })
console.log(abc) // is { a: 2, b: 2, c: 3 }
const ab = { a: 1, b: 2 }
const assignABDefaults = assignDefaults(ab)
const abc = assignABDefaults({ a: 2, c: 3 })
console.log(abc) // is { a: 2, b: 2, c: 3 }

One common case is to assign default options. Below, we write a function that greets someone. By default we greet "<Name>" with "How are you?"

Try It

const defaults = {
  name: '<Name>',
  message: 'How are you?',
}

const getOptsWithDefaults = assignDefaults(defaults)

const greet = opts => {
  const { name, message } = getOptsWithDefaults(opts)
  console.log(`Hello ${name}.  ${message}`)
}

greet({ name: 'Grace' })
// prints "Hello Grace.  How are you?
type Options = {
  name: string
  message: string
}

const defaults = {
  name: '<Name>',
  message: 'How are you?',
}

const getOptsWithDefaults = assignDefaults(defaults)

const greet = (opts: Partial<Options>) => {
  const { name, message } = getOptsWithDefaults(opts)
  console.log(`Hello ${name}.  ${message}`)
}

greet({ name: 'Grace' })
// prints "Hello Grace.  How are you?

Try It

const defaults = {
  name: '<Name>',
  message: 'How are you?',
}

const getOptsWithDefaults =
  assignDefaults(defaults)

const greet = opts => {
  const { name, message } =
    getOptsWithDefaults(opts)
  console.log(`Hello ${name}.  ${message}`)
}

greet({ name: 'Grace' })
// prints "Hello Grace.  How are you?
type Options = {
  name: string
  message: string
}

const defaults = {
  name: '<Name>',
  message: 'How are you?',
}

const getOptsWithDefaults =
  assignDefaults(defaults)

const greet = (opts: Partial<Options>) => {
  const { name, message } =
    getOptsWithDefaults(opts)
  console.log(`Hello ${name}.  ${message}`)
}

greet({ name: 'Grace' })
// prints "Hello Grace.  How are you?