[Chartjs]-Chart.js creating a line graph using dates

by

40👍

✅

You have to move your data within a dataset. If you take a look at the usage manual, a datasets array is used. The "hint" for datasets within the docs for time is also not that obvious (See headline).

See the snippet below:

I just copied the basic usage example and inserted the data from your first attempt (+ added few labels)

UPDATE 18.03.2020

I’ve updated the snippet to use Chart.js 2.8.0 and added following code, as suggested in the comment by @Erik

options: {
    scales: {
      xAxes: [{
        type: 'time'
      }]
    }
  }

UPDATE 16.02.2021

As pointed out by @habib, the 2.9.4 version was throwing couple of errors. I guess that those were caused by missing dependency (moment.js). See:

Note: starting v2.8, Moment.js is an optional dependency for Chart.js and Chart.min.js. In order to use the time scale with Moment.js, you need to make sure Moment.js is fully loaded before requiring Chart.js. You can either use a shim

Source

Therefore, I changed following things:

  • Updated Chart.js to 2.9.4
  • Added moment.js (2.29.1) as dependency
  • Adjusted the time format to be ISO8601 compliant (As suggested by soiboi)
var ctx = document.getElementById("examChart").getContext("2d");

var myChart = new Chart(ctx, {
  type: 'line',
  options: {
    scales: {
      xAxes: [{
        type: 'time',
      }]
    }
  },
  data: {
    labels: ["2015-03-15T13:03:00Z", "2015-03-25T13:02:00Z", "2015-04-25T14:12:00Z"],
    datasets: [{
      label: 'Demo',
      data: [{
          t: '2015-03-15T13:03:00Z',
          y: 12
        },
        {
          t: '2015-03-25T13:02:00Z',
          y: 21
        },
        {
          t: '2015-04-25T14:12:00Z',
          y: 32
        }
      ],
      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
    }]
  }
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chart.js@2.9.4/dist/Chart.min.js"></script>
<div class="container">
  <canvas id="examChart"></canvas>
</div>

10👍

Building on what @RamizWachtler has answered, you can add to the options section of the chart to scale the times out properly. I’ll note that this doesn’t seem to work with Charts.js 2.3. Added a working snippet that uses the latest Charts.js version as of April 2019.

Additionally I’ve changed the time formatting to be ISO8601 compliant.

var chart = new Chart(ctx, {
    type: 'line',
    data: data,
    options: {
        scales: {
            xAxes: [{
                type: 'time',
                distribution: 'linear'
            }]
        }
    }
});

Source – https://www.chartjs.org/docs/latest/axes/cartesian/time.html

var ctx = document.getElementById("examChart").getContext("2d");

var myChart = new Chart(ctx, {
  type: 'line',
  data: {
    labels: ["2015-03-15T13:03:00Z", "2015-03-25T13:02:00Z", "2015-04-25T14:12:00Z"],
    datasets: [{
      label: 'Demo',
      data: [{
          t: "2015-03-15T13:03:00Z",
          y: 12
        },
        {
          t: "2015-03-25T13:02:00Z",
          y: 21
        },
        {
          t: "2015-04-25T14:12:00Z",
          y: 32
        }
      ],
      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
    }]
  },
  options: {
    scales: {
      xAxes: [{
        type: 'time',
        distribution: 'linear'
      }]
    }
  }
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.8.0-rc.1/Chart.bundle.js"></script>
<div class="container">
  <canvas id="examChart"></canvas>
</div>

1👍

when using time, you have to use UTC time, as your local time is added(australia +10 hours / 36000 secs) so every country has a different time zone.
the key is to use moment.utc in any conversion of time
0 seconds = moment.utc(‘1970-01-01 00:00:00’)

use moment.utc('1970-01-01').add(3600, 'seconds')to add a value and then
from y-axis values or tool tip items, you have to reference

callback: value => {
    date = moment.utc(value);
    if(date.diff(moment.utc('1970-01-01 23:59:59'), 'minutes') === 0) 
    {
        return null;
    };
    date.format('HH:mm:ss');
}

label: (item, data) => data.datasets[item.datasetIndex].label +" "+ 
moment.utc(data.datasets[item.datasetIndex].data[item.index]).format("HH:mm:ss")

https://lopeys.com/ironman/IMAUS_Charts_StackedTimes.htm

0👍

My suggestion would be to add the moment.js library to your project and format your dates using moment. Also I’m not sure about using the “t” and “y” here. I’d add the time as labels and matched that with the x data: 

var data = {
  labels: [moment().format("YYYY-MM-DD"), moment().format("YYYY-MM-DD"), moment().format("YYYY-MM-DD")],
  datasets: [
    {
        data: [12,21,32],
    }
  ]
};

var myBarChart = Chart.Line(canvas,{
data:data,
});

There is a fiddle example here.

Leave a comment