javascript - Is there a way in a donut Chart.JS to show a % out of 100 - Stack Overflow

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I have a donut chart showing a number. However is there a way which the donut chart can be out of 100%, so the number I give in the data section: say 21, will show 21% plete out of 100?

Image to show desired oute:

So the donut ring is greyed out and the coloured section is how much has been pleted (or what number we allocate to the data section, I've been looking at the documentation and cannot see a way this can be done?

Code I have currently:

<canvas id="Chart1" style="width=5 height=5"></canvas>
<?php
    $var = 3;
?>

    var ctx = document.getElementById('Chart1').getContext('2d');
    var chart = new Chart(ctx, {
    // The type of chart we want to create
    type: 'doughnut',

    // The data for our dataset
        data: {
            labels: ['% Complete'],
            datasets: [{
                label: 'chart1',
                backgroundColor: 'rgb(102, 178, 255)',
                borderColor: 'rgb(102, 178, 255)',
                // Below I just pull out 1 number from the db
                data: [<?php echo $var ?>] 
            }]
        },
    });

My code outputs the below (so the 3 fills up the whole donut), whereas I would like it show 3% out of 100% plete.

I have a donut chart showing a number. However is there a way which the donut chart can be out of 100%, so the number I give in the data section: say 21, will show 21% plete out of 100?

Image to show desired oute:

So the donut ring is greyed out and the coloured section is how much has been pleted (or what number we allocate to the data section, I've been looking at the documentation and cannot see a way this can be done?

Code I have currently:

<canvas id="Chart1" style="width=5 height=5"></canvas>
<?php
    $var = 3;
?>

    var ctx = document.getElementById('Chart1').getContext('2d');
    var chart = new Chart(ctx, {
    // The type of chart we want to create
    type: 'doughnut',

    // The data for our dataset
        data: {
            labels: ['% Complete'],
            datasets: [{
                label: 'chart1',
                backgroundColor: 'rgb(102, 178, 255)',
                borderColor: 'rgb(102, 178, 255)',
                // Below I just pull out 1 number from the db
                data: [<?php echo $var ?>] 
            }]
        },
    });

My code outputs the below (so the 3 fills up the whole donut), whereas I would like it show 3% out of 100% plete.

• javascript
• charts
• chart.js
• donut-chart

Share Improve this question Follow edited Mar 30, 2020 at 16:41 xo. asked Mar 30, 2020 at 16:27 xo.xo. 48533 silver badges1111 bronze badges 1

• Wele to StackOverflow - Please read our How to Ask page and edit your question to improve it. Good questions tend to receive quicker, better answers from the munity. For starters, please include a minimal reproducible example to your question that includes all the code you have so far. – blurfus Commented Mar 30, 2020 at 16:31

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2 Answers 2

Sorted by: Reset to default 3

Try passing data of [3, 97]. You're trying to use it as a loading indicator but it seems designed for showing 100% of things broken into parts.

If you pass simply [3], then that's 100% of your dataset

Create a two value dataset, like:

[percent_value, 100-percent_value]

Here's a full demo:

const originalDoughnutDraw = Chart.controllers.doughnut.prototype.draw;

Chart.helpers.extend(Chart.controllers.doughnut.prototype, {
  draw: function() {
    const chart = this.chart;
    const {
      width,
      height,
      ctx,
      config
    } = chart.chart;

    const {
      datasets
    } = config.data;

    const dataset = datasets[0];
    const datasetData = dataset.data;
    const pleted = datasetData[0];
    const text = `${pleted}% pleted`;
    let x, y, mid;

    originalDoughnutDraw.apply(this, arguments);

    const fontSize = (height / 350).toFixed(2);
    ctx.font = fontSize + "em Lato, sans-serif";
    ctx.textBaseline = "top";


    x = Math.round((width - ctx.measureText(text).width) / 2);
    y = (height / 1.8) - fontSize;
    ctx.fillStyle = "#000000"
    ctx.fillText(text, x, y);
    mid = x + ctx.measureText(text).width / 2;
  }
});


var context = document.getElementById('myChart').getContext('2d');
var percent_value = 3;
var chart = new Chart(context, {
  type: 'doughnut',
  data: {
    labels: ['Completed', 'Pending'],
    datasets: [{
      label: 'First dataset',
      data: [percent_value, 100 - percent_value],
      backgroundColor: ['#00baa6', '#ededed']
    }]
  },
  options: {}
});

<script src="https://cdn.jsdelivr/npm/[email protected]"></script>
<canvas id="myChart"></canvas>

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