TimeLine render code triples the view if extended into a child class

[neddongo]

I wish to extend the TimeLine component's render function. If I extend the class and have render as follows:
render() { return TimeLine.prototype.render.call(this);
Then the calendar displays normally.

However, if I copy the contents of the render function from TimeLine.js into my child class's render() function, the calendar repeats itself across the screen multiple times:

How can I avoid this happening? I have already imported all the correct modules.