Chart.js 3.7.1 - How can I control the number of ticks on the y axis of a line chart? - chart.js3

Question

The data will always be integers between -10 and 10, including 0 so there could be a maximum of 21 'intervals' on the y axis.
Regardless of the data, I need the y axis to display from -10 to 10 (including 0) in increments of 1. So I need a total of 21 (ticks?) on the y axis regardless of the data.
I tried this, per the docs:
I also tried it without the steps param:
options: {
scales: {
y: {
max: -10,
min: 10,
ticks: {
steps: 21,
stepSize: 1
}
}
}
}
This is what I got:

Answer 1

The missing part in your code is autoSkip: false.
y: {
max: 10,
min: -10,
ticks: {
stepSize: 1,
autoSkip: false
}
}
According to the Chart.js documentation, autoskip is true by default.
autoskip: If true, automatically calculates how many labels can be shown and hides labels accordingly. (...) Turn autoSkip off to show all labels no matter what.
Please take a look at below runnable code and see how it works.
new Chart('canvas', {
type: 'line',
data: {
labels: ['A', 'B', 'C', 'D', 'E', 'F'],
datasets: [{
label: 'Dataset 1',
data: [3, 9, 7, 5, 9, 2],
backgroundColor: 'rgba(255, 99, 132, 0.2)',
borderColor: 'rgb(255, 99, 132)',
fill: false
},
{
label: 'Dataset 2',
data: [1, 2, -3, -5, -2, 1],
backgroundColor: 'rgba(255, 159, 64, 0.2)',
borderColor: 'rgb(255, 159, 64)'
}
]
},
options: {
scales: {
y: {
max: 10,
min: -10,
ticks: {
stepSize: 1,
autoSkip: false
}
}
}
}
});
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