How to set custom header for PouchDB ajax requests?-open source projects pouchdb/pouchdb

I’m using PouchDB 3.2.1. I’m trying to set Authorization header for all ajax requests:

db.local = new $window.PouchDB(POUCHDB_NAME);

db.remote = new $window.PouchDB(COUCHDB_URI, {
    skipSetup: true,
    ajax: {
        headers: {
            'Authorization': 'Basic ' + $window.btoa('admin:admin')
        }
    }
});

// Replication
db.local.sync(db.remote, {
    live : true,
    retry: true
});

But it doesn’t works. See the screenshot: