I saw this as an example about Dart, the programming language which is essentially JavaScript a la Google. Have look at this page for the code and a demo.

The EMT code is much easier.

n=1:1000; r=sqrt(n); t=2*pi*n/((1+sqrt(5))/2); ...
x=r*cos(t); y=r*sin(t); ...
fullwindow;  ...
plot2d(x,y,>points,color=rgb(0.9,0.8,0),style="o#",<grid):

Admittedly, the code at the linked demo page does a bit more. It display a slider for the number of points and a Latex formula linked as PNG from some page. EMT could do that too. But it cannot run on a web page like a programming language designed to do just this. Java could do it too, but it is dead. And it could not easily interact with the rest of the page, mostly because of security concerns.