How to pick latest item per user from an array in Javascript? For example, I have an array like this: [ { "data": "some data", "user": "A", "createdAt":"2016-12-24", }, { "data": "some data2", "user": "B", "createdAt":"2016-12-24", }, { "data": "some data3", "user": "A", "createdAt":"2016-12-25", }, { "data": "some data4", "user": "A", "createdAt":"2016-12-23", }, { "data": "some data5", "user": "B", "createdAt":"2016-12-25", }, { "data": "some data6", "user": "C", "createdAt":"2016-12-24", }, ] I only need the latest created item per one user, so I need an