直接上代碼：

    let str = '{"phoneNumber":"13812341234","veriCode":"12345678","expireDate":"2033-03-03 00:00:00"}'
    let json = JSON.parse(str)
    console.log(json)
    let str2 = JSON.stringify(json)
    console.log(str2)

需注意，字符串變量str中對象屬性和值用雙引號
let json = JSON.parse(str)，字符串轉(zhuǎn)JSON對象
console.log(json)，輸出JSON對象如下：

{phoneNumber: "13812341234", veriCode: "12345678", expireDate: "2033-03-03 00:00:00"}
expireDate: "2033-03-03 00:00:00"
phoneNumber: "13812341234"
veriCode: "12345678"

let str2 = JSON.stringify(json)，JSON對象轉(zhuǎn)字符串
console.log(str2)，輸出字符串如下：

{"phoneNumber":"13812341234","veriCode":"12345678","expireDate":"2033-03-03 00:00:00"}