数组转字符串join(),字符串转数组split()

数组转字符串join()
join()方法用于把数组中的所有元素放入一个字符串

arr =  ["get","post","put"]
let string=(arr).join(',')
string="get,post,put"

字符串转数组split()

split()方法用于把一个字符串分割成字符串数组

string = "get、post、put"
let arr = (string).split(',')
arr  = ["get","post","put"]