How do I access chart specific ticks formatter from the label callback?

[simzikov]

Say I have a chart:

  new Chart(foo, {
    type: 'bar',
    options: {
      scales: {
        y: {
          ticks: {
            callback: function (val) {
              return val + '%';
            },
          },
        },
      },
    },
    data: {
      labels: [...],
      datasets: [...],
    },
  });

This formats the value of the y axis label, however doesn't affect the context.formattedValue value specified in a Chart.defaults.plugins.tooltip.callbacks.label callback. Previously I used this._chart.options.scales.yAxes[x].ticks.callback to access it from the callback. However, this callback doesn't seem to be available in the label callback anymore. Am I missing something? Thanks so much for your hard work on this library!

[kurkle]

You are missing the scales configuration change. We don't have yAxes anymore.

    plugins: {
      tooltip: {
        callbacks: {
          label(ctx) {
            const scale = ctx.chart.scales.y;
            return scale.options.ticks.callback.apply(scale, [ctx.parsed.y, 0, []]);
          }
        }
      },

Off topic: Linear scale formats its "label" using options.locale