未捕获的TypeError：无法读取未定义的属性'arrayToDataTable'

Question

//google.charts.load('current', { 'packages': ['corechart'] });
//google.charts.setOnLoadCallback(displayDonut());

var displayDonut = function () {
    var elementId = '';
    var inputData = [];
    $('.donutChart').each(function (i, value) {
        elementId = value.getAttribute('id');
        $.ajax({
            url: "/Home/getChartData",
            dataType: "json",

            type: "GET",
            contentType: "application/json; charset=utf-8",
            success: function (response) {
                if (inputData.length <= 0) {
                    inputData.push(["Task", "Hours"]);
                }
                $.each(response, function (key, value) {
                    inputData.push([value.Task, value.Hours]);

                });

                //console.log(inputData);
                var options = {
                    'title': '',
                    'pieHole': 0.7,
                    colors: ['#FA0A0A', '#FBD900', '#ABA2A2'],
                    pieSliceText: 'none',
                    legend: 'none'
                };
                var dataChart =new google.visualization.arrayToDataTable(inputData);

                var chart = new google.visualization.PieChart(document.getElementById(id));
                chart.draw(dataChart, options);

            }
        });


    });
};


google.charts.load('current', { 'packages': ['corechart'] });
google.charts.setOnLoadCallback(displayDonut());

error:
customchart.js:32 Uncaught TypeError: Cannot read property 'arrayToDataTable' of undefined
    at Object.success (customchart.js:32)
    at c (jquery.min.js:2)
    at Object.fireWith [as resolveWith] (jquery.min.js:2)
    at l (jquery.min.js:2)
    at XMLHttpRequest.<anonymous> (jquery.min.js:2)