You cannot store key value without String Format.
LocalStorage only support String format for key/value.
That is why you should convert your data to string whatever it is Array or Object.
To Store data in localStorage first of all stringify it using JSON.stringify() method.
var myObj = [{name:"test", time:"Date 2017-02-03T08:38:04.449Z"}];
localStorage.setItem('item', JSON.stringify(myObj));
Then when you want to retrieve data , you need to parse the String to Object again.
var getObj = JSON.parse(localStorage.getItem('item'));
Hope it helps.