This file I created just as a personal challenge. I make a point to try something new and different every day, and this file I took as a challenge merely because I came across a Desmos version (see it here). I prefer posting with GeoGebra as it seems to give me a bit more control. With GeoGebra I can label items on the graph and have decent control over what appears in different circumstances.
Desmos does a very good job filling the role of graphing calculator, and does it with a much better resolution than the typical handheld calculator. But, I have to be honest, GeoGebra does a lot more. (I should say it can do a whole lot more: it does have a steep learning curve at the start. It is this learning curve that encourages me to push for GeoGebra's use at young ages. A steep slope becomes less steep if it is lengthened. Any ramp user knows that.)
For the moment: I have included in the GeoGebra graph the focus and directrix and a drag-able way of showing the relationship between them and the parabola itself. The equation is also present. I have not found a way of including those features (with labels) in Desmos' embeddable graph. Help me if you can!!