ChartJS New Lines '\n' in X axis Labels or Displaying More Information Around Chart or Tooltip with ChartJS V2

Question

I'm using chart.js (V2) to try to build a bar chart that has more information available to user without having to hover over or click anywhere. I've provided two examples of how I hope to edit my chart.

Two edited versions of what I hope to achieve

As can be seen, I hope to place (somewhere), some extra information outside of the labels. I had hope that by adding '\n' to the labels I might have been able to get what I was looking for similar to option A.

Some edited code is provided blow:

var barChartData = {

        labels: playerNames,
        datasets: [{
            label: 'Actual Score/Hour',
            backgroundColor: "rgba(0, 128, 0,0.5)",
            data: playerScores
          }, {
            label: 'Expected Score/Hour',
            backgroundColor: "rgba(255,0,0,0.5)",
            data: playerExpected
        }]
    };
function open_win(linktosite) {
           window.open(linktosite)
      }
        canvas.onclick = function(evt){
            var activePoints = myBar.getElementsAtEvent(evt);
            console.log(activePoints);
            linktosite = 'https://www.mytestsite.com/' + activePoints[1]['_model']['label'];
            open_win(linktosite);
}; 
window.onload = function() {
        var ctx = document.getElementById("canvas").getContext("2d");
        window.myBar = new Chart(ctx, {
            type: 'bar',
            data: barChartData,
            options: {
                title:{
                    display:true,
                    text:"Player Expected and Actual Score per Hour"
                },
                tooltips: {
                    mode: 'label'
                },
                responsive: true,
                scales: {
                    xAxes: [{
                        stacked: false,
                    }],
                    yAxes: [{
                        stacked: false
                    }]
                },
                animation: {
                    onComplete: function () {
                        var ctx = this.chart.ctx;
                        ctx.textAlign = "center";
                        Chart.helpers.each(this.data.datasets.forEach(function (dataset) {

                            Chart.helpers.each(dataset.metaData.forEach(function (bar, index) {
                                // console.log("printing bar" + bar);
                                ctx.fillText(dataset.data[index], bar._model.x, bar._model.y - 10);
                                }),this)
                                }),this);
                    }
                }
            }
        });
        // Chart.helpers.each(myBar.getDatasetMeta(0).data, function(rectangle, index) {
        // rectangle.draw = function() {
        //     myBar.chart.ctx.setLineDash([5, 5]);
        //     Chart.elements.Rectangle.prototype.draw.apply(this, arguments);
        //     }
        // }, null);            
    };

At this point I'd be satisfied with having the extradata anywhere on the bar. Any help would be appreciated. Thanks~

Answer 1

If you are using Chart.js v2.7.1, the above solution might not work.

The solution that actually worked for us was adding a small plugin right in the data and options level:

const config = {
  type: 'bar',
  data: {
    // ...
  },
  options: {
    // ...
  },
  plugins: [{
    beforeInit: function (chart) {
      chart.data.labels.forEach(function (label, index, labelsArr) {
        if (/\n/.test(label)) {
          labelsArr[index] = label.split(/\n/)
        }
      })
    }
  }]
};

A full description of how to fix this issue can be found here.

Answer 2

var config = {
  type: 'line',
  data: {
    labels: [["January","First Month","Jellyfish","30 of them"], ["February","Second Month","Foxes","20 of them"], ["March","Third Month","Mosquitoes","None of them"], "April", "May", "June", "July"],
    datasets: [{
      label: "My First dataset",
      data: [65, 40, 80, 81, 56, 85, 45],
      backgroundColor: "rgba(255,99,132,0.2)",
    }, {
      label: "My Second dataset",
      data: [40, 80, 21, 56, 85, 45, 65],
      backgroundColor: "rgba(99,255,132,0.2)",
    }]
  },
  scales : {
      xAxes : [{
          gridLines : {
              display : false,
              lineWidth: 1,
              zeroLineWidth: 1,
              zeroLineColor: '#666666',
              drawTicks: false
          },
          ticks: {
              display:true,
              stepSize: 0,
              min: 0,
              autoSkip: false,
              fontSize: 11,
              padding: 12
          }
      }],
      yAxes: [{
          ticks: {
              padding: 5
          },
          gridLines : {
              display : true,
              lineWidth: 1,
              zeroLineWidth: 2,
              zeroLineColor: '#666666'
          }
      }]
  },
                    spanGaps: true,
                    responsive: true,
                    maintainAspectRatio: true
};

var ctx = document.getElementById("myChart").getContext("2d");
new Chart(ctx, config);

<div class="myChart">
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.bundle.js"></script>

<canvas id="myChart"></canvas>
          </div>

If a label is an array as opposed to a string i.e. [["June","2015"], "July"] then each element is treated as a separate line. The appropriate calculations are made to determine the correct height and width, and rotation is still supported.

charJS version 2.7.2 used this also works in https://github.com/jtblin/angular-chart.js

Answer 3

Chart.js v2.1.5 allows for multi-line labels using nested arrays (v2.5.0 fixes it for radar graphs):

...
data: {
    labels: [["Jake", "Active: 2 hrs", "Score: 1", "Expected: 127", "Attempts: 4"], 
             ["Matt", "Active: 2 hrs", "Score: 4", "Expected: 36", "Attempts: 4"]],
    ...

However, this does mean that you will have to pre-calculate the label values.

Answer 4

With Chart.js v2.1, you can write a chart plugin to do this

---

Preview

---

Script

Chart.pluginService.register({
    beforeInit: function (chart) {
        var hasWrappedTicks = chart.config.data.labels.some(function (label) {
            return label.indexOf('\n') !== -1;
        });

        if (hasWrappedTicks) {
            // figure out how many lines we need - use fontsize as the height of one line
            var tickFontSize = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].ticks.fontSize, Chart.defaults.global.defaultFontSize);
            var maxLines = chart.config.data.labels.reduce(function (maxLines, label) {
                return Math.max(maxLines, label.split('\n').length);
            }, 0);
            var height = (tickFontSize + 2) * maxLines + (chart.options.scales.xAxes[0].ticks.padding || 0);

            // insert a dummy box at the bottom - to reserve space for the labels
            Chart.layoutService.addBox(chart, {
                draw: Chart.helpers.noop,
                isHorizontal: function () {
                    return true;
                },
                update: function () {
                    return {
                        height: this.height
                    };
                },
                height: height,
                options: {
                    position: 'bottom',
                    fullWidth: 1,
                }
            });

            // turn off x axis ticks since we are managing it ourselves
            chart.options = Chart.helpers.configMerge(chart.options, {
                scales: {
                    xAxes: [{
                        ticks: {
                            display: false,
                            // set the fontSize to 0 so that extra labels are not forced on the right side
                            fontSize: 0
                        }
                    }]
                }
            });

            chart.hasWrappedTicks = {
                tickFontSize: tickFontSize
            };
        }
    },
    afterDraw: function (chart) {
        if (chart.hasWrappedTicks) {
            // draw the labels and we are done!
            chart.chart.ctx.save();
            var tickFontSize = chart.hasWrappedTicks.tickFontSize;
            var tickFontStyle = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].ticks.fontStyle, Chart.defaults.global.defaultFontStyle);
            var tickFontFamily = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].ticks.fontFamily, Chart.defaults.global.defaultFontFamily);
            var tickLabelFont = Chart.helpers.fontString(tickFontSize, tickFontStyle, tickFontFamily);
            chart.chart.ctx.font = tickLabelFont;
            chart.chart.ctx.textAlign = 'center';
            var tickFontColor = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].fontColor, Chart.defaults.global.defaultFontColor);
            chart.chart.ctx.fillStyle = tickFontColor;

            var meta = chart.getDatasetMeta(0);
            var xScale = chart.scales[meta.xAxisID];
            var yScale = chart.scales[meta.yAxisID];

            chart.config.data.labels.forEach(function (label, i) {
                label.split('\n').forEach(function (line, j) {
                    chart.chart.ctx.fillText(line, xScale.getPixelForTick(i + 0.5), (chart.options.scales.xAxes[0].ticks.padding || 0) + yScale.getPixelForValue(yScale.min) +
                        // move j lines down
                        j * (chart.hasWrappedTicks.tickFontSize + 2));
                });
            });

            chart.chart.ctx.restore();
        }
    }
});

and then

...
data: {
    labels: ["January\nFirst Month\nJellyfish\n30 of them", "February\nSecond Month\nFoxes\n20 of them", "March\nThird Month\nMosquitoes\nNone of them", "April", "May", "June", "July"],
         ...

Note - we assume that the maximum content of one line will fit between the ticks (i.e. that no rotation logic is needed. I'm sure it's possible to incorporate rotation logic too, but it would be a tad more complicated)

You should format the tooltips to not show the x axis label, or format it to show a shorter version of the label.

---

Fiddle - http://jsfiddle.net/m0q03wpy/