Saving OfficeJS Add-In state across all documents?

Question

I know that I can save Add-In state per document using document.settings.

Is there a way to save state (e.g. active license) across documents for the same Add-In?

Answer 1

How you save user state depends on your needs.

If you want to track per-machine state you can save the data in HTML5 Local Storage.

If you want to track per-user state for signed-in users (no matter what machine or document they use), you should save their User ID and state on your database. For my own add-in, I implemented this design with Firebase:

function readUserStateAsync(customerId, callback){
    var myUserReference = firebase.database().ref("myCustomers/" + customerId);
    myUserReference.once('value').then(function(userState) {
        callback(userState.val());
    });
}

function writeUserStateAsync(customerId, userState, callback){
    var myUserReference = firebase.database().ref("myCustomers");
    myUserReference.child(customerId).set(userState, function(){ callback("success"); });
}

-Michael Saunders, program manager for Office add-ins