Implement a Custom Promise Class

You are required to implement a custom Promise.

Promise is an object that represent the eventual completion or failure of an asynchronous operation. Promise can be in 3 states:

• Pending: The initial state, neither fulfilled nor rejected.
• Fulfilled: The operation completed successfully.
• Rejected: The operation failed

Example

let promise = new Promise((resolve, reject) => {
  // Asynchronous operation
  let success = true; // Assume the operation succeeds

  if (success) {
    resolve("Operation successful!");
  } else {
    reject("Operation failed!");
  }
});

// Example of Usage
promise
  .then((result) => {
    console.log(result); // "Operation successful!"
  })
  .catch((error) => {
    console.error(error); // "Operation failed!"
  })
  .finally(() => {
    console.log("Operation completed."); // This runs no matter what
  });