I have a function-returning function. The inner function makes use of the parent function’s argument in its body. Then I make a list of functions produced by calling the parent function with different arguments. Here is an example:

function f(a) { return function(b) { return a * a + b; }; }
var fList = [f(-2), f(-1), f(0), f(1), f(2)];

Those are from a library and I cannot modify them.

I was wondering if there is any possibility to apply a filter on the fList based on the value of parent function argument. For example can I get the items in fList where the f function is called with a non-negative value? I tried inspecting fList[0] in debug console but could not make any progress unfortunately.

I feel like this is not possible. However, since when I call fList[0](2) it uses the a variable’s value of -2, I am hoping so.

Please do not suggest using an inverse function, that’s why I made it return the square of the searched argument plus the inner one. Above is an over-simplified example and the body in the real case is much different with some side effects.