Such scenario is known as, "
Offline web applications". You create an offline application that operates without any problem and allows your clients or users to work as they would work with your application. The only thing that doesn't work is online content access. For example,
Google Drive works in the same way.
W3.Org has also written a documentation for the standard to create offline web applications. There are many techniques, such as storing the data in
localStorage
objects, and when internet access is available you upload that data to server and store it or if you are having any other idea you can use that one also. Read
this documentation on W3.Org[
^] and also read the references that they have provided you with.
For more on
localStorage
, please read this
MDN documentation[
^].