set

Immutable modification operator that adopts immutable approach to modify data.

Type Definition

type set = <T>(setter: (value: T) => void) => (observable$: Observable<T>) => Observable<T>

Parameters

• setter: Modifier function that receives a value parameter, directly modifies this parameter to change the value

Details

• Uses the limu library's produce function to ensure original data is never modified
• Supports plain objects, arrays, Map, Set, and other object types
• For primitive types (string, number, boolean, etc.), returns the original value unchanged

Examples

Object Modification

import { $, set } from 'fluth'

const stream$ = $()
const modifiedStream$ = stream$.pipe(
  set((draft) => {
    draft.age = 26
  })
)

const initialData = { name: 'Alice', age: 25 }
stream$.next(initialData)

console.log(modifiedStream$.value) // { name: 'Alice', age: 26 }
console.log(initialData.age) // 25 (original data unchanged)

Array Modification

import { $, set } from 'fluth'

const stream$ = $()
const modifiedStream$ = stream$.pipe(
  set((draft) => {
    draft.items.push(4)
    draft.metadata.count = draft.items.length
  })
)

const initialData = { items: [1, 2, 3], metadata: { count: 3 } }
stream$.next(initialData)

console.log(modifiedStream$.value.items) // [1, 2, 3, 4]
console.log(modifiedStream$.value.metadata.count) // 4
console.log(initialData.items) // [1, 2, 3] (original array unchanged)