将对象或者数组或者对象数组转换成字符串------JSON.stringify
let obj= {name:'ming',age:18}
console.log(JSON.stringify(obj));
let obj= [{name:'ming',age:18},{name:'wang',age:19}]
console.log(JSON.stringify(obj));
将字符串转回数组-------JSON.parse( str)
let str= '{"name":"ming","age":18},{"name":"wang","age":19}'
console.log(JSON.parse(str));