How to make a blur effect when drawing a line on canvas?

Question

JavaScript

I need to achieve the following painting effect on canvas:


Gradient line of 3 colors.
I found a solution for drawing a gradient line and this is what happened:


I didn’t really go into it, but the essence of the solution seems to be this:
When the mouse moves from one point to another, circles are drawn using the plotLine function. The getColor function is used to calculate the color of the circle.
I tried to add blurs to the drawn circles via ctx.shadowBlur, but it didn't work. I also tried to assign to the circles not the color itself obtained by the getColor function, but a radial gradient from the resulting color passing from the center outward to transparency 0, but it also did not work.

Here is the code:
https://codepen.io/h3ckphy/pen/xxrQGLz

Answer 1

c.style.webkitFilter = "blur(3px)";