1 単純な折れ線

<!doctype html>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.8.0/Chart.min.js"></script>
<canvas id="x"></canvas>
<!-- ここはHTML -->
<script>
// ここにプログラム
new Chart("x",{
    type: "line",
    data: {
        labels: [1,2,3,4],
        datasets: [ 
            {data: [20,30,40,10]}
        ]
    },
});
</script>

HTMLファイルへの直リンク

2 2つのデータ系列(棒グラフ)

<!doctype html>
<meta charset="utf-8"/>
<script src='https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.min.js'></script>

<canvas id="myChart"></canvas>
<script>
  var ctx = document.getElementById("myChart").getContext('2d');
  var myBarChart_01 = new Chart(ctx, {
    type: 'bar',
    data: {
      labels: ["A", "B", "C", "D", "E"],
      datasets: [{
        data: [60, 40, 10, 90, 50, 30],
      },{
        data: [60, 40, 10, 20, 30, 30],
      }]
    },
  });
</script>

HTMLファイルへの直リンク