Dynamically created SVG not working in Firefox

I am not very familiar with SVG. What I am trying to do is to create SVG elements dynamically using javascript. My code is working fine in Chrome, Safari and IE, but it's not working in Firefox. You can see it in this embedded section. What could be the cause of this issue?

See the Pen VYqxoj by shijir (@shijir99) on CodePen.