pick

從對象中選擇指定的屬性，創建新對象。

語法

pick<T, K extends keyof T>(
  object: T,
  keys: K[]
): Pick<T, K>

參數

• object (T): 源對象
• keys (K[]): 要選擇的屬性鍵數組

返回值

• Pick<T, K>: 包含指定屬性的新對象

示例

基本用法

import { pick } from 'radash'

const user = {
  id: 1,
  name: 'Alice',
  email: 'alice@example.com',
  age: 25,
  city: 'New York'
}

const userInfo = pick(user, ['name', 'email'])
// { name: 'Alice', email: 'alice@example.com' }

選擇單個屬性

import { pick } from 'radash'

const product = {
  id: 123,
  name: 'Laptop',
  price: 999,
  category: 'Electronics'
}

const productName = pick(product, ['name'])
// { name: 'Laptop' }

選擇多個屬性

import { pick } from 'radash'

const order = {
  id: 'ORD-001',
  customerId: 456,
  items: ['item1', 'item2'],
  total: 150.00,
  status: 'pending',
  createdAt: new Date()
}

const orderSummary = pick(order, ['id', 'total', 'status'])
// { id: 'ORD-001', total: 150.00, status: 'pending' }

處理嵌套對象

import { pick } from 'radash'

const user = {
  id: 1,
  profile: {
    firstName: 'Alice',
    lastName: 'Smith',
    age: 25
  },
  settings: {
    theme: 'dark',
    language: 'en'
  }
}

const userProfile = pick(user, ['profile'])
// { profile: { firstName: 'Alice', lastName: 'Smith', age: 25 } }

處理不存在的屬性

import { pick } from 'radash'

const user = {
  name: 'Alice',
  age: 25
}

const result = pick(user, ['name', 'email', 'age'])
// { name: 'Alice', age: 25 }
// 注意：不存在的屬性 'email' 會被忽略

處理空對象

import { pick } from 'radash'

const emptyObj = {}
const result = pick(emptyObj, ['name', 'age'])
// {}

處理空鍵數組

import { pick } from 'radash'

const user = {
  name: 'Alice',
  age: 25
}

const result = pick(user, [])
// {}

處理函數屬性

import { pick } from 'radash'

const component = {
  name: 'Button',
  render: () => '<button>Click me</button>',
  props: { text: 'Click me' }
}

const componentInfo = pick(component, ['name', 'props'])
// { name: 'Button', props: { text: 'Click me' } }

處理數組屬性

import { pick } from 'radash'

const user = {
  id: 1,
  name: 'Alice',
  hobbies: ['reading', 'swimming'],
  tags: ['developer', 'frontend']
}

const userBasic = pick(user, ['name', 'hobbies'])
// { name: 'Alice', hobbies: ['reading', 'swimming'] }

處理日期屬性

import { pick } from 'radash'

const event = {
  id: 1,
  title: 'Meeting',
  date: new Date('2023-01-01'),
  duration: 60,
  attendees: ['Alice', 'Bob']
}

const eventInfo = pick(event, ['title', 'date'])
// { title: 'Meeting', date: new Date('2023-01-01') }

處理布爾值屬性

import { pick } from 'radash'

const user = {
  id: 1,
  name: 'Alice',
  isActive: true,
  isAdmin: false,
  email: 'alice@example.com'
}

const userStatus = pick(user, ['isActive', 'isAdmin'])
// { isActive: true, isAdmin: false }

處理null和undefined值

import { pick } from 'radash'

const user = {
  name: 'Alice',
  email: null,
  phone: undefined,
  age: 25
}

const userContact = pick(user, ['email', 'phone', 'age'])
// { email: null, phone: undefined, age: 25 }

處理Symbol屬性

import { pick } from 'radash'

const sym = Symbol('key')

const obj = {
  [sym]: 'value',
  name: 'Alice',
  age: 25
}

const result = pick(obj, [sym, 'name'])
// { [Symbol(key)]: 'value', name: 'Alice' }

處理復雜對象

import { pick } from 'radash'

const complexObject = {
  id: 1,
  metadata: {
    createdAt: new Date(),
    version: '1.0.0'
  },
  data: {
    items: [1, 2, 3],
    total: 100
  },
  config: {
    theme: 'dark',
    language: 'en'
  }
}

const essentialData = pick(complexObject, ['id', 'metadata', 'data'])
// {
//   id: 1,
//   metadata: { createdAt: new Date(), version: '1.0.0' },
//   data: { items: [1, 2, 3], total: 100 }
// }

處理API響應

import { pick } from 'radash'

const apiResponse = {
  data: {
    users: [
      { id: 1, name: 'Alice', email: 'alice@example.com' },
      { id: 2, name: 'Bob', email: 'bob@example.com' }
    ],
    total: 2,
    page: 1,
    limit: 10
  },
  status: 200,
  message: 'Success',
  timestamp: new Date()
}

const userData = pick(apiResponse, ['data', 'status'])
// {
//   data: { users: [...], total: 2, page: 1, limit: 10 },
//   status: 200
// }

處理表單數據

import { pick } from 'radash'

const formData = {
  firstName: 'Alice',
  lastName: 'Smith',
  email: 'alice@example.com',
  password: 'secret123',
  confirmPassword: 'secret123',
  terms: true
}

const publicInfo = pick(formData, ['firstName', 'lastName', 'email'])
// { firstName: 'Alice', lastName: 'Smith', email: 'alice@example.com' }

注意事項

1. 不可變性: 不會修改原對象
2. 類型安全: 支持完整的 TypeScript 類型推斷
3. 不存在的屬性: 會忽略不存在的屬性
4. 淺拷貝: 只進行淺拷貝，嵌套對象會共享引用

與其他函數的區別

• pick: 選擇指定的屬性
• omit: 排除指定的屬性
• keys: 獲取對象的所有鍵
• values: 獲取對象的所有值

性能

• 時間復雜度: O(n)，其中 n 是鍵的數量
• 空間復雜度: O(n)
• 適用場景: 數據過濾、API響應處理