### Problem Statement
You are tasked with implementing a polyfill for the `Array.map()` method in JavaScript. The goal is to replicate the functionality of the native `Array.map()` method, which creates a new array by applying a provided function to each element of the array.

Write a function named `map` that takes a callback function as its argument and returns a new array with the results of applying the callback function to each element of the original array.
<br/>
Your polyfill should support the following:

1. Accept an optional second argument, which will be used as the value of `this` when executing the callback function.
2. Handle the three parameters that the callback function receives: currentValue, index, and the array itself.


complete.test.js

index.js

partial.test.js

Polyfill for Array.map()

Here's a detailed explanation of the provided solution code:

```javascript
export const map = function (arr, callbackFn) {
  const output = [];
  arr.forEach((element, index) => {
    output.push(callbackFn(element, index, this));
  });
  return output;
};
```

### Approach:

1- The **map** function is defined as an exportable function. It takes two parameters:
- **arr:** The original array on which the map operation will be performed.
- **callbackFn:** The callback function that will be applied to each element of the array.

2-  Inside the function, a new array named **output** is initialized to store the results of applying the callback function to each element of the original array.

3- The **forEach** method is used to iterate over each element of the **arr** array. For each element, the callback function **(callbackFn)** is called with three arguments:

- **element:** The current element of the array being processed.
- **index:** The index of the current element within the array.
- **this:** The value of **this** is not explicitly specified here, so it will default to **undefined** or the global object, depending on whether the function is called in strict mode.

4-  Inside the callback function, the **callbackFn** is invoked with three arguments:

- **element:** The current element of the original array.
- **index:** The index of the current element within the original array.
- **this:** The value of **this** is passed as the third argument to the callback function. This allows the callback function - to access the specified context if provided.

5- The result of each invocation of the callback function is pushed into the **output** array.

6- Finally, the **map** function returns the **output** array, which contains the results of applying the callback function to each element of the original array.
<br/>
This implementation mimics the behavior of the native **Array.map()** method by creating a new array with the results of applying the provided callback function to each element of the original array, while also supporting the optional **this** context and the three parameters **(currentValue, index, and the array itself`)** passed to the callback function.