set()

Category

Utilities

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SSR

SSR support

Last updated: 24/04/2026

Overview

set mutates a plain object tree target in place: it splits path on . (dropping empty segments), walks to the parent of the final key, and assigns value. If an intermediate key is missing or holds a non-object value, it creates a new empty {} and replaces that slot so the path can continue-it does not merge with existing primitives in place beyond that replace. The return is the same reference target for chaining. It only supports string keys in the path (no raw brackets for array indices). Use for imperative form drafts or plugins; for React state prefer immutable updates unless you control a mutable draft (e.g. Immer-style) separately.

What it accepts

1. target: Record<string, unknown> - mutated
2. path: string - dot-separated
3. value: unknown

What it returns

• The same target reference after mutation

Usage

Build a nested config in one object with dot paths; read with UI to verify.

import { useState } from 'react'
import set from '@dedalik/use-react/utils/set'

function Example() {
  const [draft, setDraft] = useState<Record<string, unknown>>({})

  const apply = () => {
    setDraft((prev) => {
      const next = { ...prev }
      set(next, 'alerts.email.enabled', true)
      set(next, 'alerts.slack.webhook', 'https://example.com/hook')
      return next
    })
  }

  return (
    <div>
      <button type='button' onClick={apply}>
        Apply nested settings
      </button>
      <p>alerts: {String(draft.alerts != null)}</p>
    </div>
  )
}

export default function Demo() {
  return <Example />
}

API Reference

set

Signature: set(target: Record<string, unknown>, path: string, value: unknown): Record<string, unknown>

Copy-paste hook

TypeScript

/**
 * Sets nested property value by dot-separated path on target object.
 */
export default function set(target: Record<string, unknown>, path: string, value: unknown): Record<string, unknown> {
  const keys = path.split('.').filter(Boolean)
  if (keys.length == 0) return target

  let cursor: Record<string, unknown> = target

  for (let i = 0; i < keys.length - 1; i += 1) {
    const key = keys[i]
    const next = cursor[key]
    if (typeof next === 'object' && next !== null) {
      cursor = next as Record<string, unknown>
      continue
    }

    const created: Record<string, unknown> = {}
    cursor[key] = created
    cursor = created
  }

  cursor[keys[keys.length - 1]] = value
  return target
}

JavaScript

/**
 * Sets nested property value by dot-separated path on target object.
 */
export default function set(target, path, value) {
  const keys = path.split('.').filter(Boolean)
  if (keys.length == 0) return target

  let cursor = target

  for (let i = 0; i < keys.length - 1; i += 1) {
    const key = keys[i]
    const next = cursor[key]
    if (typeof next === 'object' && next !== null) {
      cursor = next
      continue
    }

    const created = {}
    cursor[key] = created
    cursor = created
  }

  cursor[keys[keys.length - 1]] = value
  return target
}