Progress Notifications In Ecmascript Promise

Are you familiar with ECMAScript promises but wondering how to incorporate progress notifications into your code? Progress notifications allow you to communicate the status of a promise's execution, which can be incredibly useful when you want to keep users informed about the progress of asynchronous operations. In this article, we will walk you through how to implement progress notifications in ECMAScript promises, so you can enhance the user experience and add a layer of transparency to your applications.

In ECMAScript, promises represent the eventual completion or failure of an asynchronous operation. Promises have three states: pending, fulfilled, and rejected. However, by default, promises do not provide any built-in mechanism for tracking the progress of an operation. This is where progress notifications come in handy.

To enable progress notifications in ECMAScript promises, you can leverage the `notify` method. This method allows you to notify listeners of the progress of an operation by providing updates as the operation progresses. The `notify` method takes a progress value as an argument and broadcasts this value to all registered listeners.

When creating a promise with progress notifications, you need to define a custom Promise class that extends the standard Promise class and includes the `notify` method. Here's an example implementation:

Javascript

class ProgressPromise extends Promise {
  notify(progress) {
    this.dispatchEvent(new CustomEvent('progress', {
      detail: { progress },
    }));
  }
}

In this custom `ProgressPromise` class, the `notify` method dispatches a custom event named 'progress' with the progress value as a detail. This allows you to listen for progress updates and react accordingly in your application.

To use the `ProgressPromise` class with progress notifications in your code, you can create a new instance of the class and chain `then` handlers to handle the progress updates along with the fulfillment and rejection of the promise. Here's an example:

Javascript

const promiseWithProgress = new ProgressPromise((resolve, reject) =&gt; {
  let progress = 0;
  const interval = setInterval(() =&gt; {
    progress += 10;
    promiseWithProgress.notify(progress);
    if (progress &gt;= 100) {
      clearInterval(interval);
      resolve('Operation completed');
    }
  }, 1000);
});

promiseWithProgress.then((result) =&gt; {
  console.log(result);
}).catch((error) =&gt; {
  console.error(error);
}).on('progress', (event) =&gt; {
  console.log(`Progress: ${event.detail.progress}%`);
});

In this example, we create a `promiseWithProgress` instance of the `ProgressPromise` class that notifies listeners of the progress every second until the operation is completed. We handle the progress updates, fulfillment, and rejection of the promise using `then` and `catch` handlers, as well as listen for the 'progress' event to log the progress updates.

By implementing progress notifications in ECMAScript promises, you can provide users with real-time updates on the status of asynchronous operations, improve the user experience, and create more transparent and engaging applications. Experiment with progress notifications in your code and see how they can enhance the functionality of your applications. Happy coding!

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