google.charts.load('current', {packages: ['geochart'], mapsApiKey: 'secretkey',callback: requestMap});

    function requestMap() {
         setupMap = true;
    }

    function drawMap(settings) {
     //Method to just draw map. Not all code.
     var chart = new google.visualization.GeoChart
    }

    function loadRegions(containerId, response,label, regionDataUrl, refresh, postData) {

        if (!geoCharts[containerId] || refresh) {
            var settings = resetGeoChartConfig(containerId);
            var options = settings.options;
            var dat = new google.visualization.DataTable(); <-- Where error is thrown
            dat.addColumn('string', 'Country');
            dat.addColumn('number', label);
            dat.addColumn('string', 'Display');
            for (var i = 0; i < response.d.length; i++) {
                    dat.addRows
                    ([
                        [response.d[i].Point, response.d[i].Value, response.d[i].Label]
                    ]);

            }

            var formatter = new google.visualization.PatternFormat('{1}');
            formatter.format(dat, [0, 2]);

            //settings reformatted e.g.
            settings.data = dat;
            settings.label = label;
            settings.zoomed = false;
            drawMap(settings, true);

        } else {
            var settings = getGeoChartConfig(containerId);
            drawMap(settings, true);
    }
function resetChart(containerId) {

        var settings = geoCharts[containerId];
        $.ajax({
            type: 'POST',
            url: settings.regionDataUrl,
            data: JSON.stringify(settings.postData),
            contentType: 'application/json; charset=utf-8',
            dataType: 'json',
            success: function (msg) {
                loadRegions(settings.containerId, msg, settings.label, settings.regionDataUrl, true, settings.postData);
            }
        });
    }

<script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>