如何使用Chart.JS创建线形图(未填充)

<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>

<canvas id="lineChart"></canvas>

var ctx = document.getElementById('lineChart').getContext('2d');

var data = {
  labels: ['January', 'February', 'March', 'April', 'May', 'June'],
  datasets: [{
    label: 'Sales',
    data: [120, 150, 180, 200, 220, 250],
    borderColor: 'blue',
    fill: false
  }]
};

var options = {
  title: {
    display: true,
    text: 'Sales Chart'
  },
  scales: {
    yAxes: [{
      ticks: {
        beginAtZero: true
      }
    }]
  }
};

var lineChart = new Chart(ctx, {
  type: 'line',
  data: data,
  options: options
});

lineChart.update();