Return value from javascript promise to calling function

Question

I am working on Ionic Project and have a two functions login() and fetchUser(). Where fetchUser() get data from SQlite database and return a promise.

fetchUser(storage){
    return new Promise(function(resolve, reject){
        storage.get('user')
        .then((user) => {
            if(user != null){
                resolve(user);
             }
           })
        .catch(err => reject(err));
    })
}

And login funciton is like this.

login(){
         this.fetchUser(this._storage)
             .then(user => {return user;})
             .catch(err => console.log(err));

// I want user data here
    }

Everything is working fine, data is fetching successfully. Now the problem is I want to return user (data) to login() function. If I call login() it returns undefined. I think this is because I an returning value from then function.

But If I log user in console in then() function then it is logging successfully. however it is not returning to the login function.