请问如何从json串中取值

请问如何从json串中取resultstr的值 求指教
如：
{"format":"QR Code","code":0,"resultStr":"1601031920000902","options":{},"canceled":0}

let jsonStr = '{"format":"QR Code","code":0,"resultStr":"1601031920000902","options":{},"canceled":0}'
let resultStr = JSON.parse(jsonStr ).resultStr

JSON.parse()

let jsons = '{"format":"QR Code","code":0,"resultStr":"1601031920000902","options":{},"canceled":0}'
let resultStr = JSON.parse(jsons).resultStr