How To Determine If A Function Has Been Called Without Setting Global Variable

Have you ever needed to keep track of whether a function has been called in your code without resorting to using a global variable? It's a common challenge in software development, but fear not, because there is a simple and elegant solution to this problem! By leveraging the power of closures and JavaScript's inner functions, you can easily determine if a function has been called without cluttering your global scope with unnecessary variables.

So, how exactly can you achieve this? Let's walk through the process step by step.

### Step 1: Define Your Function
First things first, you need to define the function you want to keep track of. Let's create a simple function called `myFunction` for demonstration purposes.

function myFunction() {
  console.log('Function has been called!');
}

### Step 2: Create a Wrapper Function
Next, we'll create a wrapper function that will encapsulate your original function along with a tracking mechanism to check if it has been called.

function trackFunctionExecution() {
  let called = false;

  return function() {
    if (!called) {
      called = true;
      myFunction();
    } else {
      console.log('Function has already been called.');
    }
  };
}

const trackedFunction = trackFunctionExecution();

### Step 3: Call the Tracked Function
Now, every time you want to execute `myFunction`, you should call `trackedFunction` instead. This wrapper function will ensure that `myFunction` is only called once.

trackedFunction(); // Output: "Function has been called!"
trackedFunction(); // Output: "Function has already been called."

### Step 4: Test It Out
To confirm that the tracking mechanism is working as expected, try calling `trackedFunction` multiple times and observe the output. You should see that the message changes after the first call.

By following these steps, you can easily determine if a function has been called without resorting to global variables. This approach encapsulates the tracking logic within a closure, keeping your code clean and organized.

### Conclusion
In conclusion, using closures and inner functions is a powerful technique that can help you solve common coding challenges like tracking function calls without cluttering your code with global variables. By following the steps outlined in this article, you can implement a simple yet effective solution to determine if a function has been called. So go ahead, give it a try in your next project and see the benefits for yourself!