此数组想保留彼数组的数据，可通过push()方法。

方法1.数组换位。

let arr = []
const arr1 = [1, 2, 3, 4, 5, 6]
arr = arr1
console.log(arr)

//但这种方式有弊端,前面保留的数据会被后面的数据给替换掉
const arr2 = [2, 7]
arr = arr2
console.log(arr)

方法2：for of循环遍历。

let arr = []
const arr1 = [1, 2, 3, 4, 5, 6]
for (let number of arr1) {
    const temp = arr.push(number)
    console.log(temp)
}

let arr = []
const arr1 = [1]
const temp = arr.push(...arr1)
console.log(temp)

// let arr = []
// const arr1 = [1, 2]
// const temp = arr.push(...arr1)
// console.log(temp)

// let arr = []
// const arr1 = [1, 2, 3]
// const temp = arr.push(...arr1)
// console.log(temp)