数组拼接

var arr1 = [1, 2, 3]
var arr2 = [4, 5, 6]

析构赋值

arr1.push(...arr2)
console.log(arr1)
// [1, 2, 3, 4, 5, 6]

concat 方法

var arr3 = arr1.concat(arr2)
var arr3 = arr1.concat(...arr2, 7, 8, [9, 10])
var arr3 = arr1.concat(arr2, 7, 8, [9, 10])

数组遍历

for (let i of arr2) {
  arr1.push(i)
}