ChartJS onClick parameters

bodnarescu.diana · March 11, 2025, 2:32pm

Hello,

I am currently using ChartJS 2024.3.2 with Servoy 2024.3.5.3948_LTS.
I have encountered an issue with the onClick event of a bar chart where the dataset_index and index parameters consistently return the following values:
dataset_index: 0
index: null
However, when I check the value of context.dataIndex within a tooltip callback, it correctly reflects the index values (0, 1, 2, etc.).

Could someone please confirm if this behavior is a bug or if my expectations are incorrect?

seain · March 14, 2025, 4:54am

I confirmed the same behaviour in 2024.12.

I believe it is a bug, if you look at their code that handles the onClick event, they use selected._index instead of selected.index when passing to the API method. You should submit a bug report.

github.com/Servoy/svyChartJS

svychartjs/projects/svychartjs/src/chart/chart.ts

master


      
              const dataset = this.chart.chart.getElementsAtEventForMode(e.native,'dataset', { intersect: true }, false);
              if (!dataset[0]) return;
              //get selected dataset index (helps distinguish between multiple datasets)
              const firstdataset = dataset[0];
              const datasetIndex = firstdataset.datasetIndex;
              const selected: any = activePoints[datasetIndex];
              if (!selected) return;
              const label = this.chart.chart.data.labels[selected.index];
              const value = this.chart.chart.data.datasets[selected.datasetIndex].data[selected.index];
              if (this.onClick) {
                  this.onClick(datasetIndex, selected._index, label.toString(), value as number, e.native);
              }
          }
          
          generateLegend(): string {
              //TODO how can we do this in chart.js 3.x
              return null;
              //return this.chart.chart.generateLegend().toString();
          }
          
          getChartAsImage(): string {

bodnarescu.diana · March 14, 2025, 7:25am

Thank you, Seain, for confirming.

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ChartJS onClick parameters

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