ES6展开语法Spread syntax（...）

let arr = [1,3,5,7,9]
console.log(...arr) // 1 3 5 7 9

let arr1 = [1,3,5,7,9]
let arr2 = [2,4,6,8,10]
let arr3 = [...arr1, ...arr2]
console.log(arr3) // [1,3,5,7,9,2,4,6,8,10]

function sum(...numbers) {
  return numbers.reduce((pre, cur) => {
    return pre + cur
  })
}
console.log(sum(1,2,3,4,5)) // 15

let person = {name: 'swt', age: 20}
let person2 = {...person}
person.name = 'mff'
console.log(person2) // {name: "swt", age: 20}
console.log(person) // {name: "mff", age: 20}

let person = {name: 'swt', age: 20}
let person2 = { ...person, name:  'mff', address: 'china' }
console.log(person2) // {name: "mff", age: 20, address: "china"}