deriveKey

Derive new object keys by a mapping and construct a new object.

Use this when you want to keep the original keys and add extra derived keys to the result.

Usage

import { deriveKey } from 'rattail'

deriveKey({ value: 1, label: 'Option A' }, { label: 'tooltip' })
// return { value: 1, label: 'Option A', tooltip: 'Option A' }

const options = [{ value: 'a', label: 'Option A' }]

options.map((option) => deriveKey(option, { label: 'tooltip' }))
// return [{ value: 'a', label: 'Option A', tooltip: 'Option A' }]

const id = Symbol('id')
const key = Symbol('key')

deriveKey(
  {
    [id]: 1,
    name: 'rattail',
  },
  { [id]: key, name: 'label' },
)
// return { [id]: 1, [key]: 1, name: 'rattail', label: 'rattail' }

Arguments

Arg	Type	Defaults
object	object
mapping	object

Return

Type
object

Notes

• Returns a new object and does not mutate the original object.
• Keys not present in mapping are preserved as-is.
• Supports both string keys and symbol keys.
• If a derived target key already exists, the derived value overwrites it.
• Unlike rekey, deriveKey keeps the original key and adds a new key.