js如何翻转一个字符串&&js如何清除数组

[xiaohesong]

翻转字符串

How to reverse a string in JavaScript

const str = "hello"
str.split('').reverse().join('')
//"olleh"

const str = "hello"
[...str].reduce((prev,next)=>next+prev)
//"olleh"

function reverseString(str){
  const arr = [...str]
  let reverse= "";
  while(arr.length){
     reverse = reverse + arr.pop()
  }
  return reverse
}

清空数组

How to clear an array in javascript

var arr = [1,2,3,4,5,6] 
arr = [ ]
console.log(arr)
//empty array [ ] 

var arr = [1,2,3,4,5,6]
arr.length = 0
console.log(arr)
//empty array [ ]

var arr = [1,2,3,4,5,6]
while(arr.length){
   arr.pop()
}
console.log(arr)
//empty array [ ]