Javascript - Chartjs 4 - Fill area between stacked line and bar chart

user1639283
February 3, 2024
238 views
0 votes
2 Answers

I’m in the process of migrating over to chart.js 4.4.1 and in the prior version (2.9.4) I was able to fill the gap with a color as in the attached image.

2.9.4 sample img

In the newest version, I’m able to get close by using an opacity, but it’s not quite the same:
4.4.1 sample img

Any ideas on how to make that happen? I’m using the non-module JavaScript chartjs file.

See my test code below.

<canvas id="my-chart"></canvas>


    <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.4.1/chart.umd.js"></script>
    <script>
        
        let labels = [];
        for (let year=2000; year <= 2010; year++) {
            labels.push(year);
        }

        const config = {
            data: {
                labels: labels,
                datasets: [
                    {
                        type: "bar",
                        label: "Product",
                        data: [1331320,2851137,5952127,6607851,11068289,12059067,12117998,11827962,16582836,20184478,23915606],
                        backgroundColor: "#bec38f",
                        order: 1
                    },
                    {
                        backgroundColor: "rgba(151,156,106,0.5)",// "#979c6a",
                        borderColor: "#826f68",
                        borderWidth: 3,
                        data: [1242306,2442693,5070218,5502960,8572948,7722718,6916448,7196356,10429229,12544283,15149568],
                        label: "Benchmark",
                        type: "line",
                        fill: true,
                        pointBackgroundColor: "#ffffff",
                        pointRadius: 5,
                        order: 0
                    }
                ]
            },
            options: {
                scales: {
                    x: {
                        grid: {
                            display: false
                        }
                    },
                    y: {
                        stacked: true,
                        scaleLabel: {
                            display: false
                        },
                        ticks: {
                            callback: function(value, index, ticks) {
                                return ("$" + (value/1000000));
                            }
                        }
                    }
                },
                plugins: {
                    tooltip: {
                        intersect: true,
                        callbacks: {
                            label: function(context) {
                                return ("$" + context.parsed.y.toString().replace(/B(?=(d{3})+(?!d))/g, ","));
                            }
                        }
                    }
                }
            }
        };

        new Chart(document.getElementById("my-chart"), config);

    </script>

Answers

I think the behaviour of 2.9.4 was erronous, to draw the fill at the bottom and the line on top?

The only way I can think of to replicate that result, is to duplicate the
line dataset, that is to have one instance of the dataset for the fill on the first level (order = 0) and another instance of the same dataset for the line and points on top, (order = 2). This can can be done without duplicating the actual dataset object literal, in an update to the chart:

const chart = new Chart(document.getElementById("my-chart"), config);
const dataset1 = chart.data.datasets[1];
chart.data.datasets.push({
    ...dataset1,
    data: [...dataset1.data],
    label: '', // we'll disable the legend and tooltip for datasets with empty labels
    order: 2,
    fill: true
}) 
chart.update();

That has to be accompanied by some code to exclude the duplicate dataset
from the tooltip and legend; we’ll identify this dataset by its empty label. Also, the stacked behaviour of the y axis has to be disabled. Here’s a full snippet:

let labels = [];
for (let year=2000; year <= 2010; year++) {
    labels.push(year);
}

const config = {
    data: {
        labels: labels,
        datasets: [
            {
                type: "bar",
                label: "Product",
                data: [1331320,2851137,5952127,6607851,11068289,12059067,12117998,11827962,16582836,20184478,23915606],
                backgroundColor: "#bec38f",
                order: 1
            },
            {
                backgroundColor: "#979c6a", //"rgba(151,156,106,0.5)",// "#979c6a",
                borderColor: "#826f68",
                borderWidth: 3,
                data: [1242306,2442693,5070218,5502960,8572948,7722718,6916448,7196356,10429229,12544283,15149568],
                label: "Benchmark",
                type: "line",
                fill: false,
                drawActiveElementsOnTop: true,
                pointBackgroundColor: "#ffffff",
                pointRadius: 5,
                order: 0
            }

        ]
    },
    options: {
        scales: {
            x: {
                grid: {
                    display: false
                }
            },
            y: {
                stacked: false,
                scaleLabel: {
                    display: false
                },
                ticks: {
                    callback: function(value, index, ticks) {
                        return ("$" + (value/1000000));
                    }
                }
            }
        },
        plugins: {
            tooltip: {
                intersect: true,
                callbacks: {
                    label: function(context) {
                        if(!context.dataset.label){
                            return null
                        }
                        return ("$" + context.parsed.y.toString().replace(/B(?=(d{3})+(?!d))/g, ","));
                    }
                }
            },
            legend:{
                labels: {
                    filter({text}){
                        return !!text
                    }
                }
            }
        }
    }
};

const chart = new Chart(document.getElementById("my-chart"), config);
const dataset1 = chart.data.datasets[1];
chart.data.datasets.push({
    ...dataset1,
    data: [...dataset1.data],
    label: '',
    order: 2,
    fill: true,
})
chart.update();

<canvas id="my-chart"></canvas>

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.4.1/chart.umd.js"></script>

You can set the drawTime of the filler plugin to beforeDatasetsDraw by adding the following config to the plugins section of the config object:

filler: {
  drawTime: 'beforeDatasetsDraw'
},

Live example:

let labels = [];
for (let year = 2000; year <= 2010; year++) {
  labels.push(year);
}

const config = {
  data: {
    labels: labels,
    datasets: [{
        type: "bar",
        label: "Product",
        data: [1331320, 2851137, 5952127, 6607851, 11068289, 12059067, 12117998, 11827962, 16582836, 20184478, 23915606],
        backgroundColor: "#bec38f",
        order: 1
      },
      {
        backgroundColor: "#979c6a",
        borderColor: "#826f68",
        borderWidth: 3,
        data: [1242306, 2442693, 5070218, 5502960, 8572948, 7722718, 6916448, 7196356, 10429229, 12544283, 15149568],
        label: "Benchmark",
        type: "line",
        fill: true,
        pointBackgroundColor: "#ffffff",
        pointRadius: 5,
        order: 0
      }
    ]
  },
  options: {
    scales: {
      x: {
        grid: {
          display: false
        }
      },
      y: {
        stacked: true,
        scaleLabel: {
          display: false
        },
        ticks: {
          callback: function(value, index, ticks) {
            return ("$" + (value / 1000000));
          }
        }
      }
    },
    plugins: {
      filler: {
        drawTime: 'beforeDatasetsDraw'
      },
      tooltip: {
        intersect: true,
        callbacks: {
          label: function(context) {
            return ("$" + context.parsed.y.toString().replace(/B(?=(d{3})+(?!d))/g, ","));
          }
        }
      }
    }
  }
};

new Chart(document.getElementById("my-chart"), config);

<canvas id="my-chart"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/4.4.1/chart.umd.js"></script>

Documentation

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Javascript – Chartjs 4 – Fill area between stacked line and bar chart

Answers