get element attribute value in Protractor

I'm writing a Protractor test that has to wait for an element attribute to have a non-empty value and then I want to return that value to the caller function. This has proven to be more difficult to write than I expected!

I am able to correctly schedule a browser.wait() command to wait for the element attribute to have a non-empty value and I have verified that this value is in fact what I am expecting to get inside the callback function, but for some reason, I am not able to return that value outside of the callback function and onto the rest of the test code.

Here is how my code looks like:

function test() {
    var item = getItem();
    console.log(item);
}

function getItem() {
    var item;
    browser.wait(function() {
        return element(by.id('element-id')).getAttribute().then(function(value) {
            item = value;
            // console.log(item);
            return value !== '';
        });
    });
    return item;
}

I can tell that the order of execution is not as I expect it to be, because when I uncomment the console.log() call inside the callback function, I see the expected value printed out. However, the same call in the test() function prints 'undefined'.

What is going on here? What am I missing? How can I get the attribute value out of the callback function properly?

I appreciate your help.