title: ChartJS 'Line chartjs' does not show output in NodeRED?
body: <p>My requirement is to output 2 y-axis chart with real-time data readings in NodeRED. I have installed <code>ChartJS</code> package in NodeRED and now according to the documentation of the package there should be <code>PATH, Title, X-Axis, Y-Axis,  Payload</code>. But I couldn't find the <code>Payload</code> tab anywhere in the <code>Line Chartjs</code> node?</p>
  <p><a href="https://i.stack.imgur.com/n5aEJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/n5aEJ.png" alt="enter image description here" /></a></p>
  <p>Ref : <a href="https://www.npmjs.com/package/node-red-contrib-chartjs" rel="nofollow noreferrer">https://www.npmjs.com/package/node-red-contrib-chartjs</a></p>
  <p><a href="https://i.stack.imgur.com/KoleG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KoleG.png" alt="enter image description here" /></a></p>
  <p>So I assumed that I have to add the code which belonged to <code>Payload</code> inside a function node before the <code>Line Chartjs node</code>.</p>
  <p>What I have tried : (my function node)</p>
  <pre><code>var left = {payload : msg.payload.readResults[0].v };
  var right = {payload : msg.payload.readResults[1].v };
  
  
  //return [[left,right]];
  
  
  const labels = [1,2,3,4,5,6,7,8,9,10];
  const data = {
    labels: labels,
    datasets: [
      {
        label: 'Dataset 1',
        data: left,
        borderColor: '#ff0000',
        backgroundColor: '#ff0000',
        yAxisID: 'leftCamber',
      },
      {
        label: 'Dataset 2',
        data: right,
        borderColor: '#0000ff',
        backgroundColor: '#0000ff',
        yAxisID: 'rightCamber',
      }
    ]
  };
  
  const config = {
    type: 'line',
    data: data,
    options: {
      responsive: true,
      interaction: {
        mode: 'index',
        intersect: false,
      },
      stacked: false,
      plugins: {
        title: {
          display: true,
          text: 'Chart.js Line Chart - Multi Axis'
        }
      },
      scales: {
        leftCamber: {
          type: 'linear',
          display: true,
          position: 'left',
        },
        rightCamber: {
          type: 'linear',
          display: true,
          position: 'right',
  
          // grid line settings
          grid: {
            drawOnChartArea: false, // only want the grid lines for one axis to show up
          },
        },
      }
    },
  };
  
  const actions = [
    {
      name: 'CamberGraph',
      handler(chart) {
        chart.data.datasets.forEach(dataset =&gt; {
          dataset.data = chart.data.labels.length
        });
        chart.update();
      }
    },
  ];
  
  
  </code></pre>
  <p>Here I have tried to get the 2 HTTP outputs I've named as <code>left</code> and <code>right</code> as my datasets(2 y-axis) vs hardcoded x-axis(1 through 10) which will be <code>Footage</code> later on.</p>
  <p>PS : I have returned the <code>left</code> and <code>right</code> using return statement and it's outputting the values as I expected.</p>
  <p>Currently I do not get any output in my debug window as well as in my <code>ChartJS Line Chart</code> when I inject the node. Using what I've tried so far can anybody show where I've done wrong or add/remove anything to make the graph work?</p>
  <p>Thank you!</p>