Null checks in user validation

Question

I would like to know an alternative, more elegant way to write the following method. I am especially not enthusiastic of the nested if statement.

hasUserSavedCredentials: function () {
            var userName = Storage.get(CONFIG.app.storageUserName),
                password = Storage.get(CONFIG.app.storagePassword),
                result = false;
            if (userName !== null && password !== null) {
                if (userName.length > 0 && password.length > 0) {
                    result = true;
                    // save in state for faster retrivial
                    State.xx.isSaved = result;
                    State.xx.userName = userName;
                    State.xx.password = password;
                } else {
                    result = false;
                    State.xx.isSaved = false;
                }
            }
            return result;
        },

Answer 1

You can remove result = false;, as result is already false.

And to get rid of the nested statements, you could use early returns:

if (userName == null && password == null) {
    return false;
}

if (userName.length <= 0 && password.length <= 0) {
    State.xx.isSaved = false;
    return false;
}
State.xx.isSaved = true;
State.xx.userName = userName;
State.xx.password = password;
return true;

Is it correct that when username is null, isSaved = false should not be set? Because if not, then you could just combine the two if statements, either in my example, or in yours.

Answer 2

Seems kind of weird that you need to check null and '' from the storage value. You would think that if the storage kept a value that it would be valid. If you can't change how that works the following code could avoid an extra if check and be a little more terse:

hasUserSavedCredentials: function () {
            var userName = Storage.get(CONFIG.app.storageUserName) || '',
                password = Storage.get(CONFIG.app.storagePassword) || '',
                hasSavedCredentials = userName.length > 0 && password.length > 0

                if (hasSavedCredentials) {
                    State.xx.userName = userName;
                    State.xx.password = password;
                }
                State.xx.isSaved = hasSavedCredentials;

            return hasSavedCredentials;
        }

I am assuming storage will either return null or a string if it is found, since it null is a falsy the || will default it to ''. The extra if can be avoided because username or password will always be a string. Since there isn't an extra if check the result can be stored and used without the need for an else. Also naming result to a more descriptive value helps.