chartjs-plugin-dragData.js

A plugin for Chart.js >= 2.4.0

Makes data points draggable. Supports touch events.

Online demo single Y-Axis, dual Y-Axis,small chart,bubble chart.

Installation

npm

npm install chartjs-plugin-dragdata --save

CDN

In browsers, you may use the following script tag:

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/chartjs-plugin-dragData.min.js"></script>

Or, download a release archive file from the dist folder.

Configuration

To make (line, bubble and radar chart) data points draggable, simply add dragData: true to the config section of the chart instance. If you (additionally to the y-axis) would like to drag data along the x-axis, you may also add dragX: true.

To round the values dragged to, simply add dragDataRound: 0 to the config section of the chart instance.

• 0 will round to ..., -2, -1, 0, 1, 2, ...
• 1 will round to ..., -0.2, -0.1, 0.0, 0.1, 0.2, ...
• -1 will round to ..., -20, -10, 0, 10, 20, ...

Individual event listeners can be specified as follows:

{
  ...
  dragData: true,
  dragX: false,
  dragDataRound: 0,
  onDragStart: function (event, element) {},
  onDrag: function (event, datasetIndex, index, value) {},
  onDragEnd: function (event, datasetIndex, index, value) {}
}

When dragging data points towards the outer boundaries of the y-axis, one may experience unexptected (fast) changes to the y-axis scale. Therefore, depending on the use case, it may be recommended to fix the y-scale using similar options as follows (especially on small charts):

options: {
  scales: {
    yAxes: [{
      ticks: {
        max: 25,
        min: 0
      }
    }]
  },
  ...

To avoid dragging specific datasets, you can set dragData to false within the dataset options.

const data = {
  datasets: [
    {
      label: "Data Label",
      fill: false,
      data: dataPoints,
      yAxisID: 'B',
      dragData: false
    }, {
  ...

To avoid dragging specific scales, you can set dragData to false within the axis scale options.

options: {
  scales: {
    yAxes: [{
      ticks: {
        max: 25,
        min: 0
      },
      dragData: false
    }]
  },
  ...

To avoid dragging specific data points inside a draggable dataset, you can return false to function onDragStart.

To disable the automatic update of the data, you can return false to function onDrag. Nothing will happen to the points without you changing the data attribute somewhere else. This is use full for frameworks like emberjs who us the data down action up paradigm.

Gotchas

When working with a module bundler (e.g. Webpack) and a framework (e.g. Vue.js/React/Angular), you still need to import the plugin library after installing. Here's a small example for a Vue.js component

<template>
  <div>
    <canvas id="chart"></canvas>
  </div>
</template>
<script>
import Chart from 'chart.js'
// load the options file externally for better readability of the component.
// In the chartOptions object, make sure to add "dragData: true" etc.
import chartOptions from '~/assets/js/labour.js'
import 'chartjs-plugin-dragdata'

export default {
  data() {
    return {
      chartOptions
    }
  },
  mounted() {
    this.createChart('chart', this.chartOptions)
  },
  methods: {
    createChart(chartId, chartData) {
      const ctx = document.getElementById(chartId)
      const myChart = new Chart(ctx, {
        type: chartData.type,
        data: chartData.data,
        options: chartData.options,
      })
    }
  }
}
</script>
<style>
</style>

Contributing

Please feel free to submit an issue or a pull request!

License

chartjs-plugin-dragdata.js is available under the MIT license.