Dynamically update values of a chartjs chart

Question

I created an basic bar chart using chartjs and it works fine. Now I want to update the values on a time based interval. My problem is that after I created the chart, I do not know how to update its values correctly...

My code:

var ctx = $("#myChart").get(0).getContext("2d");

var dts = [
    {
        fillColor: "rgba(220,220,220,0.5)",
        strokeColor: "rgba(220,220,220,1)",
        data: [0, 0, 0, 0, 0]
    }
];

var data = {
    labels: ["Core#1", "Core#2", "Core#3", "Core#4", "Total"],
    datasets: dts
};

var chart = new Chart(ctx);
chart.Bar(data);

//test code
setInterval( function () {                        
    data.datasets[0].data = [random(), random(), random(), random(), random()];
    chart.Bar(data);

},2000);

in the test code, I am updating the values with datasets[0].data- is this the right way to do it? The problem with this is that everytime I call chart.Bar(), the values are reset to 0 then animated to the random value (like I am recreating the chart). This way, all animations are always from 0 to value which looks strange. I would expect that if I update a value from 50 to 10 the bar would go down to 10 from 50 and not setted to 0 then animated to 10.

I did not found anything in the docs about this... am I doing something wrong or this is impossible with this library?

Answer 1

Update: Looks like chartjs has been updated (see comment below). There are some examples up that look very nice:

1. Here's an example of updating a line chart using new data: http://jsbin.com/yitep/5/edit
2. Here's how we can update existing data on a line chart: http://jsbin.com/yitep/4/edit

Original Post

As of Nov 2013, there seem to be very few options for updating charts.

There is a good example here (duplicated below) of adding new points to a line chart. Still kind of jumpy but not too bad. However, I think the effect probably depends on the chart you are using.

It does look like this is somewhere in the development pipeline. I don't see any indication of a release date yet though: https://github.com/nnnick/Chart.js/issues/13 [Closed as of Jul 26, 2014]

JS

$(document).ready(function(){
  var count = 10;
  var data = {
      labels : ["1","2","3","4","5", "6", "7", "8", "9", "10"],
        datasets : [
          {
                fillColor : "rgba(220,220,220,0.5)",
                strokeColor : "rgba(220,220,220,1)",
                pointColor : "rgba(220,220,220,1)",
                pointStrokeColor : "#fff",
                data : [65,59,90,81,56,45,30,20,3,37]
            },
            {
                fillColor : "rgba(151,187,205,0.5)",
                strokeColor : "rgba(151,187,205,1)",
                pointColor : "rgba(151,187,205,1)",
                pointStrokeColor : "#fff",
                data : [28,48,40,19,96,87,66,97,92,85]
            }
        ]
  }
  // this is ugly, don't judge me
  var updateData = function(oldData){
    var labels = oldData["labels"];
    var dataSetA = oldData["datasets"][0]["data"];
    var dataSetB = oldData["datasets"][1]["data"];

    labels.shift();
    count++;
    labels.push(count.toString());
    var newDataA = dataSetA[9] + (20 - Math.floor(Math.random() * (41)));
    var newDataB = dataSetB[9] + (20 - Math.floor(Math.random() * (41)));
    dataSetA.push(newDataA);
    dataSetB.push(newDataB);
    dataSetA.shift();
    dataSetB.shift();    };

  var optionsAnimation = {
    //Boolean - If we want to override with a hard coded scale
    scaleOverride : true,
    //** Required if scaleOverride is true **
    //Number - The number of steps in a hard coded scale
    scaleSteps : 10,
    //Number - The value jump in the hard coded scale
    scaleStepWidth : 10,
    //Number - The scale starting value
    scaleStartValue : 0
  }

  // Not sure why the scaleOverride isn't working...
  var optionsNoAnimation = {
    animation : false,
    //Boolean - If we want to override with a hard coded scale
    scaleOverride : true,
    //** Required if scaleOverride is true **
    //Number - The number of steps in a hard coded scale
    scaleSteps : 20,
    //Number - The value jump in the hard coded scale
    scaleStepWidth : 10,
    //Number - The scale starting value
    scaleStartValue : 0
  }

  //Get the context of the canvas element we want to select
  var ctx = document.getElementById("myChart").getContext("2d");
  var optionsNoAnimation = {animation : false}
  var myNewChart = new Chart(ctx);
  myNewChart.Line(data, optionsAnimation);  

  setInterval(function(){
    updateData(data);
    myNewChart.Line(data, optionsNoAnimation)
    ;}, 2000
  );
});


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for(e=0;e<j.labels.length;e++)h=b.measureText(j.labels[e]).width,d=h>d?h:d;d+=10}r=q-d-t;m=Math.floor(r/(a.labels.length-1));n=q-t/2-r;p=g+c.scaleFontSize/2;x(c,function(){b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(q-t/2+5,p);b.lineTo(q-t/2-r-5,p);b.stroke();0<s?(b.save(),b.textAlign="right"):b.textAlign="center";b.fillStyle=c.scaleFontColor;for(var d=0;d<a.labels.length;d++)b.save(),0<s?(b.translate(n+d*m,p+c.scaleFontSize),b.rotate(-(s*(Math.PI/180))),b.fillText(a.labels[d],
0,0),b.restore()):b.fillText(a.labels[d],n+d*m,p+c.scaleFontSize+3),b.beginPath(),b.moveTo(n+d*m,p+3),c.scaleShowGridLines&&0<d?(b.lineWidth=c.scaleGridLineWidth,b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+d*m,5)):b.lineTo(n+d*m,p+3),b.stroke();b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(n,p+5);b.lineTo(n,5);b.stroke();b.textAlign="right";b.textBaseline="middle";for(d=0;d<j.steps;d++)b.beginPath(),b.moveTo(n-3,p-(d+1)*k),c.scaleShowGridLines?(b.lineWidth=c.scaleGridLineWidth,
b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+r+5,p-(d+1)*k)):b.lineTo(n-0.5,p-(d+1)*k),b.stroke(),c.scaleShowLabels&&b.fillText(j.labels[d],n-8,p-(d+1)*k)},function(d){function e(b,c){return p-d*v(a.datasets[b].data[c],j,k)}for(var f=0;f<a.datasets.length;f++){b.strokeStyle=a.datasets[f].strokeColor;b.lineWidth=c.datasetStrokeWidth;b.beginPath();b.moveTo(n,p-d*v(a.datasets[f].data[0],j,k));for(var g=1;g<a.datasets[f].data.length;g++)c.bezierCurve?b.bezierCurveTo(n+m*(g-0.5),e(f,g-1),n+m*(g-0.5),
e(f,g),n+m*g,e(f,g)):b.lineTo(n+m*g,e(f,g));b.stroke();c.datasetFill?(b.lineTo(n+m*(a.datasets[f].data.length-1),p),b.lineTo(n,p),b.closePath(),b.fillStyle=a.datasets[f].fillColor,b.fill()):b.closePath();if(c.pointDot){b.fillStyle=a.datasets[f].pointColor;b.strokeStyle=a.datasets[f].pointStrokeColor;b.lineWidth=c.pointDotStrokeWidth;for(g=0;g<a.datasets[f].data.length;g++)b.beginPath(),b.arc(n+m*g,p-d*v(a.datasets[f].data[g],j,k),c.pointDotRadius,0,2*Math.PI,!0),b.fill(),b.stroke()}}},b)},L=function(a,
c,b){var e,h,f,d,g,k,j,l,m,t,r,n,p,s,w=0;g=u;b.font=c.scaleFontStyle+" "+c.scaleFontSize+"px "+c.scaleFontFamily;t=1;for(d=0;d<a.labels.length;d++)e=b.measureText(a.labels[d]).width,t=e>t?e:t;q/a.labels.length<t?(w=45,q/a.labels.length<Math.cos(w)*t?(w=90,g-=t):g-=Math.sin(w)*t):g-=c.scaleFontSize;d=c.scaleFontSize;g=g-5-d;e=Number.MIN_VALUE;h=Number.MAX_VALUE;for(f=0;f<a.datasets.length;f++)for(l=0;l<a.datasets[f].data.length;l++)a.datasets[f].data[l]>e&&(e=a.datasets[f].data[l]),a.datasets[f].data[l]<
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d*m,p+c.scaleFontSize),b.rotate(-(w*(Math.PI/180))),b.fillText(a.labels[d],0,0),b.restore()):b.fillText(a.labels[d],n+d*m+m/2,p+c.scaleFontSize+3),b.beginPath(),b.moveTo(n+(d+1)*m,p+3),b.lineWidth=c.scaleGridLineWidth,b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+(d+1)*m,5),b.stroke();b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(n,p+5);b.lineTo(n,5);b.stroke();b.textAlign="right";b.textBaseline="middle";for(d=0;d<j.steps;d++)b.beginPath(),b.moveTo(n-3,p-(d+1)*
k),c.scaleShowGridLines?(b.lineWidth=c.scaleGridLineWidth,b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+r+5,p-(d+1)*k)):b.lineTo(n-0.5,p-(d+1)*k),b.stroke(),c.scaleShowLabels&&b.fillText(j.labels[d],n-8,p-(d+1)*k)},function(d){b.lineWidth=c.barStrokeWidth;for(var e=0;e<a.datasets.length;e++){b.fillStyle=a.datasets[e].fillColor;b.strokeStyle=a.datasets[e].strokeColor;for(var f=0;f<a.datasets[e].data.length;f++){var g=n+c.barValueSpacing+m*f+s*e+c.barDatasetSpacing*e+c.barStrokeWidth*e;b.beginPath();
b.moveTo(g,p);b.lineTo(g,p-d*v(a.datasets[e].data[f],j,k)+c.barStrokeWidth/2);b.lineTo(g+s,p-d*v(a.datasets[e].data[f],j,k)+c.barStrokeWidth/2);b.lineTo(g+s,p);c.barShowStroke&&b.stroke();b.closePath();b.fill()}}},b)},D=window.requestAnimationFrame||window.webkitRequestAnimationFrame||window.mozRequestAnimationFrame||window.oRequestAnimationFrame||window.msRequestAnimationFrame||function(a){window.setTimeout(a,1E3/60)},F={}};

HTML

<html>
    <head>
        <script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    </head>
    <body>
        <h1>Live Updating Chart.js</h1>

        <canvas id="myChart" width="400" height="150"></canvas>


    </body>
</html>

Answer 2

The update() triggers an update of the chart. chart.update( )

.update(config)

Triggers an update of the chart. This can be safely called after updating the data object. This will update all scales, legends, and then re-render the chart. A config object can be provided with additional configuration for the update process.

update() can be safely called after updating values of one or more existing points within the the data object, rendering the changes in one animated render loop.

// update the first dataset's value of 'March' to be 50
myBarChart.data.datasets[0].bars[2].value = 50;

// animate update of 'March' from 90 to 50.
myBarChart.update();

Answer 3

Here is how to do it in the last version of ChartJs:

setInterval(function(){
    chart.data.datasets[0].data[5] = 80;
    chart.data.labels[5] = "Newly Added";
    chart.update();
}

Look at this clear video

or test it in jsfiddle

Answer 4

You also can use destroy() function. Like this

 if( window.myBar!==undefined)
     window.myBar.destroy();
 var ctx = document.getElementById("canvas").getContext("2d");
 window.myBar = new Chart(ctx).Bar(barChartData, {
     responsive : true,
 });

Answer 5

You just need to change the chartObject.data.datasets value and call update() like this:

chartObject.data.datasets = newData.datasets;
chartObject.data.labels = newData.labels;
chartObject.update();

Answer 6

Remove the canvas dom and add in again.

function renderChart(label,data){

    $("#canvas-wrapper").html("").html('<canvas id="storeSends"></canvas>');
    var lineChartData = {
        labels : label,
        datasets : [
            {
                fillColor : "rgba(49, 195, 166, 0.2)",
                strokeColor : "rgba(49, 195, 166, 1)",
                pointColor : "rgba(49, 195, 166, 1)",
                pointStrokeColor : "#fff",
                data : data
            }
        ]

    }
    var canvas = document.getElementById("storeSends");
    var ctx = canvas.getContext("2d");

    myLine = new Chart(ctx).Line(lineChartData, {
        responsive: true,
        maintainAspectRatio: false
    });
}

Answer 7

If destroy() and clear() is not working (just like what i had experience) you can use jquery to remove the canvas and append it again.

    $('#chartAmazon').remove();
    $('#chartBar').append('<canvas id="chartAmazon"></canvas>');

    var ctxAmazon = $("#chartAmazon").get(0).getContext("2d");
      var AmazonChart = new Chart(ctxAmazon, {
        type: 'doughnut',
        data: dataAmazon,
        options: optionsA
    });

Answer 8

I think the easiest way is to write a function to update your chart including the chart.update()method. Check out this simple example I wrote in jsfiddle for a Bar Chart.

//value for x-axis
var emotions = ["calm", "happy", "angry", "disgust"];

//colours for each bar
var colouarray = ['red', 'green', 'yellow', 'blue'];

//Let's initialData[] be the initial data set
var initialData = [0.1, 0.4, 0.3, 0.6];

//Let's updatedDataSet[] be the array to hold the upadted data set with every update call
var updatedDataSet;

/*Creating the bar chart*/
var ctx = document.getElementById("barChart");
var barChart = new Chart(ctx, {
  type: 'bar',
  data: {
    labels: emotions,
    datasets: [{
      backgroundColor: colouarray,
      label: 'Prediction',
      data: initialData
    }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks: {
          beginAtZero: true,
          min: 0,
          max: 1,
          stepSize: 0.5,
        }
      }]
    }
  }
});

/*Function to update the bar chart*/
function updateBarGraph(chart, label, color, data) {
  chart.data.datasets.pop();
  chart.data.datasets.push({
    label: label,
    backgroundColor: color,
    data: data
  });
  chart.update();
}

/*Updating the bar chart with updated data in every second. */
setInterval(function() {
  updatedDataSet = [Math.random(), Math.random(), Math.random(), Math.random()];
  updateBarGraph(barChart, 'Prediction', colouarray, updatedDataSet);
}, 1000);

<html>

<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.3.0/Chart.min.js"></script>

<body>
    <div>
      <h1>Update Bar Chart</h1>
      <canvas id="barChart" width="800" height="450"></canvas>
    </div>
    <script src="barchart.js"></script>
  </body>
  
</head>

</html>

Hope this helps.

Answer 9

I don't think it's possible right now.

However that's a feature which should come soon, as the author hinted here: https://github.com/nnnick/Chart.js/issues/161#issuecomment-20487775

Answer 10

There's at least 2 ways of solve it:

1) chart.update()

2) Delete existing chart using chart.destroy() and create new chart object.

Answer 11

This is an example with ChartJs - 2.9.4

var maximumPoints = 5;// with this variable you can decide how many points are display on the chart
        function addData(chart, label, data) {
            chart.data.labels.push(label);
            chart.data.datasets.forEach((dataset) => {
                var d = data[0];
                dataset.data.push(d);
                data.shift();
            });


            var canRemoveData = false;
            chart.data.datasets.forEach((dataset) => {
                if (dataset.data.length > maximumPoints) {

                    if (!canRemoveData) {
                        canRemoveData = true;
                        chart.data.labels.shift();
                    }

                    dataset.data.shift();

                }

            });



            chart.update();
        }




        window.onload = function () {
            var canvas = document.getElementById('elm-chart'),
                ctx = canvas.getContext('2d');

            var myLineChart = new Chart(ctx, {
                type: 'line',
                data: {
                    labels: [],
                    datasets: [
                        {
                            data: [],
                            label: 'Dataset-1',
                            backgroundColor: "#36a2eb88",
                            borderColor: "#36a2eb",
                        },
                        {
                            data: [],
                            label: 'Dataset-2',
                            backgroundColor: "#ff638488",
                            borderColor: "#ff6384",
                        }
                    ],

                },
                options: {
                    responsive: false,
                    maintainAspectRatio: false,
                    scales: {
                        yAxes: [{
                            ticks: {
                                beginAtZero: true
                            }
                        }]
                    }
                }
            });

            var index = 0;
            setInterval(function () {

                var data = [];
                myLineChart.data.datasets.forEach((dataset) => {
                    data.push(Math.random() * 100);
                });

                addData(myLineChart, index, data);
                index++;

            }, 1000);
        }

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.min.js"></script>
<canvas id="elm-chart" width="640" height="480"></canvas>

Answer 12

The simplest way is to replace the canvas element and then call new Chart() again:

function reloadMyChart() {
    $('myChart').replaceWith('<canvas id="myChart"></canvas>');
    new Chart(document.getElementById("myChart"), {
        data: yourChartData,
        type: yourChartType,
        options: yourChartOptions
    });
}

Of course, you must replace yourChartData, yourChartType and yourChartOptions with the correct values required to initialize Chart.js. See Chart.js Docs.

You can call reloadMyChart function on a button click or any other event you need. Probably you'll add parameters to this function and use these to make a REST call to dynamically update your chart, like this:

function reloadMyChart(param1, param2) {
    $('myChart').replaceWith('<canvas id="myChart"></canvas>');
    $.get("restUrl?param1=" + param1 + "&param2=" + param2 + ",
        function(data) {
            // call new Chart() here and use returned data
        }
    );

Hope it helps! =)

Answer 13

Showing realtime update chartJS

function add_data(chart, label, data) 
      {
        var today = new Date();
        var time = today.getHours() + ":" + today.getMinutes() + ":" + today.getSeconds();
        myLineChart.data.datasets[0].data.push(Math.random() * 100);
        myLineChart.data.datasets[1].data.push(Math.random() * 100);
        myLineChart.data.labels.push(time)
        myLineChart.update();
      }
      setInterval(add_data, 10000); //milisecond

full code , you can download in description link

Answer 14

You can check instance of Chart by using Chart.instances. This will give you all the charts instances. Now you can iterate on that instances and and change the data, which is present inside config. suppose you have only one chart in your page.

for (var _chartjsindex in Chart.instances) {
/* 
 * Here in the config your actual data and options which you have given at the 
   time of creating chart so no need for changing option only you can change data
*/
 Chart.instances[_chartjsindex].config.data = [];
 // here you can give add your data
 Chart.instances[_chartjsindex].update();
 // update will rewrite your whole chart with new value
 }

Answer 15

So simple, Just replace the chart canvas element.

$('#canvas').replaceWith(' id="canvas" height="200px" width="368px">');