[Regression] getState method returns no data in event callback

[gabrielwalt]

When pushing a callback on the adobeDataLayer stack that is to be executed as soon as the adobeDataLayer object initializes, then it seems that adobeDataLayer.getState() doesn't work properly.

This worked in 1.0.0, even though incorrectly as the callbacks got called twice: once with the data not available via adobeDataLayer.getState() and once with the data available. In 1.1.0, the callback is called once only, but only with no more data available via adobeDataLayer.getState().

Steps to reproduce

Navigate to about:blank URL in a browser, and execute the following JS in the brower console:

window.adobeDataLayer = [];
instance = 0;

adobeDataLayer.push(function(dl) {
    dl.addEventListener(
        "new event", 
        function(event) {
            console.log("callback " + ++instance, dl.getState());
        }
    )
});

adobeDataLayer.push({
    event: "new event",
    context: "test"
});

acdl = document.createElement("script");
acdl.src = "https://unpkg.com/@adobe/adobe-client-data-layer@1.1.0/dist/adobe-client-data-layer.min.js";
document.body.append(acdl);

The above code incorrectly logs:

callback 1 {}

It would have been expected to log:

callback 1 { context: "test" }

When changing the adobe-client-data-layer script version to 1.0.0, then the callback gets wrongly executed twice, but the second time with the correct data available:

callback 1 {}
callback 2 { context: "test" }

This change was introduced via #92, and it seems like it didn't correctly fix the entire problem.

[jckautzmann]

With the changes from the pull request #101 the data layer always behaves the same: it does not matter whether the custom code is executed before or after the data layer script has loaded. The callback function fires just once, whether registering an event listener before or after adobe-client-data-layer.min.js has loaded.