Does anyone have a Js formula for cubic interpolation?

Question

JavaScript

I have an array with points x, y from which a graph is built in the future.

I need to get an array of intermediate points (cubic interpolation) to get a smooth graph.

I must say right away that this is not canvas.
Array of the form:

x: [1,3, 9, 27],
y: [5,12,22,35]

That is, from the point x1.y5 to the point x3.y12, I need to get an array of intermediate points.
Please tell me the formula in js to get the interpolation.

Answer 1

https://github.com/osuushi/Smooth.js