我尝试使用charts.js和json api呈现图表，但呈现的图表仅显示json中的前x和y值

使用xmlhttp提取json

var url = "https://syed1ahmed.github.io/stage-gear/api.json";
xmlhttp.open("GET", url, true);
xmlhttp.send();
xmlhttp.onreadystatechange = function () {
    if (this.readyState == 4 && this.status == 200) {
        var data = JSON.parse(this.responseText);

        date = data.data.map(function (elem) {
            return elem.x;
        })

        volume = data.data.map(function (elem) {
            return elem.y;
        })

        const ctx = document.getElementById('myChart').getContext('2d');
        const myChart = new Chart(ctx, {
            type: 'bar',
            data: {
                labels: date,
                datasets: [{
                    label: 'daily volume in USD',
                    data: volume,
                    backgroundColor: 'rgba(255, 99, 132, 1)'
                }]
            },
            options: {
                scales: {
                    y: {

                    }
                }
            }
        });

    }
}

json应用程序接口链接https://syed1ahmed.github.io/stage-gear/api.json