How read write file txt un Sencha Touch

I want to save/load app settings locally.

I put my json url in resources/url.txt file. Now I want to read that url and put in store.

How can I do that? I also want to write/edit the text in it. Any clue where to start?

I did follow this indexedDB sample guide, http://ift.tt/1yJeqSO

I can write data in indexedDB, but no clue how to read it. Please advice.

How read write file txt un Sencha Touch