JavaScript - Button Not Being Detected?

Regarding the JavaScript below, I'm not sure why when I click this button:

<button class="btn btn-mobile btn-grp-next btn-next-funding_amount mt-5" data-name="btn-grp-next" type="button"><span>CONTINUE</span> <i class="icon-arrow-thin-right"></i><i class="spinner"></i></button>

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The following code doesn't detect the "CONTINUE" button being clicked for some reason?  I do get into the function below but it is NOT passing the button element,  I get the same result as clicking anywhere on the page and NOT the continue button. The listener is attached to document.body.

var saveInfosInSessionStorage = function(event) {

    var target = event.target;
    console.log("#### ==>  target.type: " + target.type + "  ===>   target.dataset", target.dataset);
    if (target.dataset && (target.type == "button")) {
        var fType;
        if (target.dataset.value) {
            fType = target.dataset.value;
            switch (fType) {
                case "Fund Now":
                    ...
                    break;
                case "Fund Later":
                    ...
                    break;
            }

        } else if (target.dataset.name) {
            fType = target.dataset.name;
            switch (fType) {
                case "btn-grp-next":
                    console.log("============== CONTINUE BUTTON CLICKED =================");
                    break;
            }
        }
    }
};

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The console.log on line #4  shows the type as undefined and shows the data.set as "DOMStringMap" . So it acts as if I never clicked the "CONTINUE" button?
I have no idea why this is happening or how to fix?  Thanks!