index.html

<!doctype html>
<html>

<head>
  <title>Socket.IO chat</title>

</head>

<body>
  <div>
    <canvas id="myChart"></canvas>
  </div>
</body>

<script src="/socket.io/socket.io.js"></script>
<script src="https://code.jquery.com/jquery-1.11.1.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chart.js@2.8.0/dist/Chart.min.js"></script>
<script>
  $(function () {

    var socket = io();
    var canvas = document.getElementById('myChart');
    var ctx = canvas.getContext('2d');
    ctx.clearRect(0, 0, canvas.width, canvas.height);

    var options = {
      // All of my other bar chart option here
      scales: {
        yAxes: [{
          ticks: {
            beginAtZero: true
          }
        }]
      }
    }


    var myChart = new Chart(ctx, { options, data: [] });

    socket.on('client get', function (msg) {
      console.log(msg);
      let labels = [];
      let data = [];

      msg.forEach(element => {
        labels.push(element.name);
        data.push(element.votes);
      });
      refreshChart(labels, data, ctx);
    });


  });

  function refreshChart(labelArr, dataArr, ctx) {
    console.log(myChart);
    myChart = new Chart(ctx, {
      type: 'bar',
      data: {
        labels: labelArr,
        datasets: [{
          label: '# of Votes',
          data: dataArr,
          backgroundColor: [
            'rgba(255, 99, 132, 0.2)',
            'rgba(54, 162, 235, 0.2)',
            'rgba(255, 206, 86, 0.2)',
            'rgba(75, 192, 192, 0.2)',
            'rgba(153, 102, 255, 0.2)',
            'rgba(255, 159, 64, 0.2)'
          ],
          borderColor: [
            'rgba(255, 99, 132, 1)',
            'rgba(54, 162, 235, 1)',
            'rgba(255, 206, 86, 1)',
            'rgba(75, 192, 192, 1)',
            'rgba(153, 102, 255, 1)',
            'rgba(255, 159, 64, 1)'
          ],
          borderWidth: 1
        }]
      }
    });
    myChart.update();
  }


</script>


<script>


</script>


</html>