Type your function using the buttons, then press = to draw it. Remember to always put an operator between elements (no implicit multiplication) and to close all brackets.
Use the slider to adjust the scale — it's especially useful for trigonometric functions like sin and cos, which would otherwise appear completely flat.
I've wanted to make something like Desmos for years, but always assumed it was way beyond my skill level. Turns out I could have done it ages ago — it's surprisingly simple once you actually sit down and try.
I finally had the time and motivation to do it, so here it is. It's probably not going to be useful to anyone, but I had a lot of fun building it.