Offline mode in ionic-angular 2 app


How can we convert our online app into offline app in ionic 2 ?

when we are fetching all the data from the server using api’s and api’s are sending us the url’s of the images and other sort of data.

If these are the solutions :

1- couchdb + pouchdb

2- sqlite

then which one of them is the best to implement it in our ionic-angular 2 app or there is some other solution.