How can I differentiate between an arrow function, class and a normal function?

Question

How can I differentiate between these three things in ES6 using its reference?

let x = i => i+1;

class y { constructor(i) { this._i=i+1; } get i(){ retur         


        

Answer 1

You can't the first two cases get transpiled into this:

var x = function x(i) {
  return i + 1;
};

function z(i) {
  return i + 1;
}

For the last one you could check if it complains if it's a class when you call it:

function isClass(instance){
  try{
    instance()
  }catch(e){
    return e.message === "Cannot call a class as a function";
  }
  return false;
}

But that will obviously trigger the side effects of calling it, so it doesn't work in the general case.