JavaScript call function inside a function by variable name [duplicate]

Question

I'm having a difficulty calling a function inside of another function when its name is in a variable:

var obj = {}

obj.f = function() {
  var inner = {
    a: function() {
      function b() {
        alert('got it!');
      }
      b(); // WORKS AS EXPECTED
      x = 'b';
      [x](); // DOESN'T WORK, NEITHER this[x]() window[x](), etc.
    }
  }
  inner.a();
}

obj.f();

I tried prefixing [x]() with different scope paths but so far w/o success. Searching existing answers did not turn up anything. It works with this[x]() if b() is placed directly inside object inner. I would like to keep b() as a function inside function a() because of variable scope in function a(), otherwise I would need to pass many parameters to b().

//// Re duplicate question: Quentin provided a more elegant answer in this thread imo.

Answer 1

There is no sensible way of accessing an arbitrary variable using a string matching the name of the variable. (For a very poor way to do so, see eval).

[x](); // DOESN'T WORK

You're trying to call an array as a function

NEITHER this[x]()

The function isn't a property of the inner object.

window[x](), etc.

Since it isn't a global, it isn't a property of the window object either.

---

If you need to call a function based on the value of a string variable, then organise your functions in an object and access them from that.

  function b() {
    alert('got it!');
  }
  var myFunctions = {
      b: b
  };
  x = 'b';
  myFunctions[x](); 

Answer 2

Try this. Currently you are assigning string to variable x, instead of a function variable.

 x = b;
 x();