// 数组转字符串，用逗号间隔
let list=['aaa']
console.log(list.join(','))
list=['aaa','bbb','ccc']
console.log(list.join(','))
// 字符串转数组，用逗号间隔
let str='aaa'
console.log(str.split(','))
str='aaa,bbb,ccc'
console.log(str.split(','))输出：
aaa aaa,bbb,ccc ["aaa"] ["aaa", "bbb", "ccc"]
