Chart.js Usage

To create a chart using Chart.js, you need to initialize the Chart class and pass in the chart node:

HTML Canvas code, the chart display location:

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

Obtain the node through different methods:

Initialization Method

// All of the following methods work
const ctx = document.getElementById('myChart');  // Get the node
const ctx = document.getElementById('myChart').getContext('2d');  // The getContext() method returns the canvas context
const ctx = $('#myChart'); // jQuery retrieval
const ctx = 'myChart'; // Pass in the node ID

After obtaining the element node with the above code, we can create our own chart types.

In the following example, we create a simple line chart:

Example

const ctx = document.getElementById('myChart');
const labels = ['January', 'February', 'March','April', 'May', 'June', 'July'];  // Set the corresponding labels on the X axis
const data = {
  labels: labels,
  datasets: [{
    label: 'My First Line Chart',
    data: [65, 59, 80, 81, 56, 55, 40],
    fill: false,
    borderColor: 'rgb(75, 192, 192)', // Set the line color
    tension: 0.1
  }]
};
const config = {
  type: 'line', // Set the chart type
  data: data,
};
const myChart = new Chart(ctx, config);

Try it Yourself »

The output of the above example is:

The following example creates a bar chart showing votes in different colors.

Example

const ctx = document.getElementById('myChart');
const myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
        datasets: [{
            label: '# Votes',
            data: [12, 19, 3, 5, 2, 3],
            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: {
            y: {
                beginAtZero: true
            }
        }
    }
});

Try it Yourself »

The output of the above example is:

Configuration Object Structure

The common structure of the configuration object is as follows:

const config = {
  type: 'line'
  data: {}
  options: {}
  plugins: []
}

Parameter Description:

  • type-- Specify the chart type
  • data-- The dataset displayed in the chart
  • options-- Some optional configurations; different chart types have different configurations
  • plugins-- Plugins
Other Extensions