A chart can have multiple datasets. In an axis chart, every dataset is represented individually.
data: {
labels: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
datasets: [
{ name: "Dataset 1", values: [18, 40, 30, 35, 8, 52, 17, -4] },
{ name: "Dataset 2", values: [30, 50, -10, 15, 18, 32, 27, 14] }
]
},