ChartJS 4 migration: access other datasets from tooltip callback - chart.js

Question

I'm migrating from ChartJS 2.9.3 to 4.2.1 (current). By following the 3.x and 4.x migration guides, I've sorted most things out, but I've come across a problem that I don't see a solution for.
One of my charts is a stacked bar chart. There are two datasets for it:
let chartData = {
// other stuff...
datasets: [
{ label: "Has thing", data: [200, 250, etc] },
{ label: "Does not has thing", data: [10, 4, etc] },
]
}
In my tooltips, I was accessing both datasets to create a custom tooltip with the percent representation of each part of each stack. For instance, the tooltips for the first stack might say: "Has thing: 200 (95.2%)" and "Does not has thing: 10 (4.8%)". My callback function looked like this:
// other stuff
callbacks: {
label: function(tooltipItem, data) {
let dataset = data.datasets[tooltipItem.datasetIndex];
let count_with = data.datasets[0].data[tooltipItem.index]
let count_without = data.datasets[1].data[tooltipItem.index]
let total = count_with + count_without
let this_dataset_count = dataset.data[tooltipItem.index]
let this_dataset_perc = (this_dataset_count / total * 100).toFixed(1)
let label = dataset.label + ": "
label += this_dataset_count + " (" + this_dataset_perc + "%)"
return label;
}
}
Looking at the 3.x migration guide, it appears they removed the data parameter from the tooltip callback, opting instead to add the item's dataset directly to the tooltipItem. Unfortunately, they don't seem to specify how I can access other datasets.
Has this functionality simply been removed completely, or is there a different way to access it?

Answer 1

As #kikon pointed out, data is accessible via context.chart.data. For some reason, that doesn't show up for me when I console.dir() the context object so I was just completely overlooking it.
Anyway, for anyone this might help in the future, here's the working version:
callbacks: {
label: function(context) {
const datasets = context.chart.data.datasets
const countWith = datasets[0].data[context.dataIndex]
const countWithout = datasets[1].data[context.dataIndex]
const perc = (context.raw / (countWith + countWithout) * 100).toFixed(1)
return `${context.dataset.label}: ${context.formattedValue} (${perc}%)`
}
}