Can you conceal a JavaScript function within a specific scope?

Question

Can you conceal a JavaScript function within a specific scope?

Suppose I have two functions a and b that I want to keep within a certain functional scope. Since they share some common code, I decide to extract this shared functionality into another method named support.

support should be accessible by both a and b, but I prefer it not to be visible to other methods within the same scope. Is there a way to achieve this?

// This is the scope; could be global or inside another function

function a() {
  let res = support()
  res.name = "a"
  return res
}

function b() {
  let res = support()
  res.name = "b"
  return res
}

function support() {
  return {"foo": "bar", "name": "support"}
}

I had an idea while writing this, which I will share as an answer. However, it's not exactly what I'm looking for since a and b end up being function expressions instead of behaving like regular function declarations (if my terminology is correct).

javascript

Answer 1

Answer №1

While I was in the process of writing, this idea came to mind so I decided to share it as an "answer", even though it's not exactly what I originally had in mind. Essentially, I crafted an immediately invoked function expression that returns the functions a and b, assigning them respectively to the variables "a" and "b" within the appropriate scope.

let [a, b] = (function(){ 

  function helper() {
    return {"foo": "bar", "name": "helper"}
  }

  function a() { 
    let result = helper()
    result.name = "a"
    return result;
  }
    
  function b() { 
    let result = helper()
    result.name = "b"
    return result;
  }

  return [a, b]
})()

Therefore, at the higher level scope, you can call a and b, while helper remains inaccessible. It's worth noting that these top-level [a, b] aren't technically function declarations; rather, they are variables holding function expressions (as far as I understand). Consequently, calling a() before defining the variables is not possible; if a were indeed a function declared within this scope, it would be hoisted and thus callable beforehand. Ultimately, it seems like achieving what I initially hoped for may be unattainable, hence why this represents my best attempt.

Answer 2

While I was in the process of writing, this idea came to mind so I decided to share it as an "answer", even though it's not exactly what I originally had in mind. Essentially, I crafted an immediately invoked function expression that returns the functions a and b, assigning them respectively to the variables "a" and "b" within the appropriate scope.

let [a, b] = (function(){ 

  function helper() {
    return {"foo": "bar", "name": "helper"}
  }

  function a() { 
    let result = helper()
    result.name = "a"
    return result;
  }
    
  function b() { 
    let result = helper()
    result.name = "b"
    return result;
  }

  return [a, b]
})()

Therefore, at the higher level scope, you can call a and b, while helper remains inaccessible. It's worth noting that these top-level [a, b] aren't technically function declarations; rather, they are variables holding function expressions (as far as I understand). Consequently, calling a() before defining the variables is not possible; if a were indeed a function declared within this scope, it would be hoisted and thus callable beforehand. Ultimately, it seems like achieving what I initially hoped for may be unattainable, hence why this represents my best attempt.

Can you conceal a JavaScript function within a specific scope?

Answer №1

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