What Is The Equivalent Of Bluebird Promise Finally In Native Es6 Promises Duplicate

When working with promises in JavaScript, you might have come across the Bluebird promise library, which offers some handy functionalities like `.finally()`. But what if you are using native ES6 promises and need to replicate the behavior of Bluebird's `.finally()` method? In this guide, we'll explore how you can achieve similar functionality using native ES6 promises in your code.

First things first, let's understand what the `.finally()` method does in Bluebird promises. In Bluebird, `.finally()` allows you to run a specific piece of code once a promise is settled, whether it's resolved or rejected. This is useful for cleanup operations or releasing resources, regardless of the promise's outcome.

To replicate this behavior in native ES6 promises, we can leverage the `.then()` and `.catch()` methods along with the `Promise.resolve()` function. Here's an example of how you can achieve the equivalent of Bluebird's `.finally()` using native ES6 promises:

Javascript

const promise = new Promise((resolve, reject) =&gt; {
  // Your async operation here
  resolve('Success');
});

promise.then(
  (result) =&gt; {
    // On success
    console.log(result);
  }
)
.catch(
  (error) =&gt; {
    // On error
    console.error(error);
}
)
.finally(() =&gt; {
  // Cleanup or resource release operation
  console.log('Finally block executed');
});

In the above snippet, we create a new promise and handle the success and error cases using `.then()` and `.catch()`. To introduce the equivalent of Bluebird's `.finally()`, we can use the `Promise.resolve()` function to create a new promise that always resolves, regardless of the original promise's outcome. We then append a `.then()` block to perform the desired cleanup or resource release operation.

By chaining a `.then()` block after `.catch()`, we ensure that the cleanup code runs whether the promise is resolved or rejected. This mimics the behavior of the `.finally()` method in Bluebird promises.

It's worth noting that while native ES6 promises do not have a built-in `.finally()` method like Bluebird, this approach provides a straightforward way to achieve similar functionality in your code. By strategically chaining `.then()` and `.catch()` blocks, along with `Promise.resolve()`, you can effectively handle cleanup operations in a concise and readable manner.

In conclusion, when working with native ES6 promises and needing functionality akin to Bluebird's `.finally()`, you can utilize a combination of `.then()`, `.catch()`, and `Promise.resolve()` to achieve the desired behavior. This approach allows you to maintain code cleanliness and handle cleanup operations effectively. Next time you find yourself in a situation requiring a `.finally()` equivalent in native ES6 promises, remember this technique to streamline your promise-based workflows.

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