Simplest way to plot points randomly inside a circle

Question

I have a basic JSFiddle whereby I want to have random points plotted inside a circle.

But I do not know how to limit the points to be inside the circle.

This is

Answer 1

Randomly pick dSquared (0..radius^2) and theta (0..2pi), then

x = sqrt(dSquared) cos(theta)
y = sqrt(dSquared) sin(theta)