1.手写数组反转非reverse方法

偏基础类

let arr = [1,2,3,4];
let arr2 = []

while(arr.length) {
  let num = arr.pop()
  arr2.push(num)
}
console.log(arr2)

let arr = [1,2,3,4]
let arr2 = []
while(arr.length) {
  let num = arr.shift()
  arr2.unshit(num)
}
console.log(arr2)