javascriptのspread operatorのいいサンプルを見つけた

いいサンプルを見つけた
https://daveceddia.com/immutable-updates-react-redux/

// For arrays:
let nums = [1, 2, 3];
let newNums = [...nums]; // => [1, 2, 3]
nums === newNums // => false! not the same array

// For objects:
let person = {
  name: "Liz",
  age: 32
}
let newPerson = {...person};
person === newPerson // => false! not the same object

// Internals are left alone:
let company = {
  name: "Foo Corp",
  people: [
    {name: "Joe"},
    {name: "Alice"}
  ]
}
let newCompany = {...company};
newCompany === company // => false! not the same object
newCompany.people === company.people // => true!

let liz = {
  name: "Liz",
  age: 32,
  location: {
    city: "Portland",
    state: "Oregon"
  },
  pets: [
    {type: "cat", name: "Redux"}
  ]
}

// Make Liz one year older, while leaving everything
// else the same:
let olderLiz = {
  ...liz,
  age: 33
}