JSON.parse用于把jsonString转换成jsonObject:

var jsonString= '{"key":"value","key":"value"}';
var jsonObject = JSON.parse(jsonString);
console.log(jsonObject);
//输出:[object:Object]

JSON.stringify用于jsonObject转换成jsonString:

var jsonObejct = {"key":"value","key":"value"};
var jsonString = JSON.stringify(jsonObject);
console.log(jsonString);
//输出:'{"key":"value","key":"value"}'