Method for passing a formula to a JS function?

1

Hi.

I’m working on a project where I’d like to take a custom function from the user, at least ideally via an ‘input text’ box that would be passed to a JS function as a parameter and then return the transformed value.

There would be only a single independent variable (i.e. ‘x’), and the purpose of the text box would be to allow the user to make different transforms to a dataset. For example ‘x^2’, ‘x/100’, etc.

From the MDN docs I found the ‘eval()’ function which I think might suit this purpose though the docs also quickly go on to say how dangerous eval is and basically not to use it.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval

I wondered if anyone had any thoughts on how to safely accomplish this ?

2

The MDN doc goes on to tell you how to do it without eval.

3

Yeah, using eval, especially when being used for user input is dangerous.

There are JS libraries to parse formulas, like this and this. Find a free one you like or build your own.