How to use fooplot as parser?

[q2apro]

I am astonished that fooplot can "understand" so many formulas, such as sin() etc.

How would I go and use this parsing capability in my own project? What functions do I have to use?

Goal: I have an input field, that holds for example 2*sin(3*x) and I want to throw in my own x values to get the corresponding y values.

For now I am using mathjs.org but I run into some problems, also the math.min.js is 210 KB...