Asynchronous JavaScript

JavaScript is single-threaded, meaning it executes one operation at a time. However, asynchronous programming allows JavaScript to handle time-consuming tasks (e.g., fetching data, reading files) without blocking the main execution thread.

This Privacy Policy describes how Alevio ("we," "our," or "us"), founded and led by Felix Danyluk (CEO and Founder), collects, uses, and discloses your information when you use our application, website, and services (collectively, the "Service").

Important:

Alevio is designed as a privacy-first application. All your personal data is stored locally on your device and is not transferred to our servers unless you explicitly activate cloud functions.

1. Information We Collect

Alevio operates primarily as a local application.
The information stored includes:

Personal information: name and preferences (stored locally only).
Usage data: daily responses and insights (stored locally only).
Device information: app preferences and settings (stored locally only).
AI Chat data: when using AI features, conversation history is stored locally on your device.
Image data: when using vision features, uploaded images are processed locally and may be temporarily stored for AI analysis.
Generated images: DALL-E generated images are saved locally on your device for display purposes.
Usage limits: daily usage tracking for cloud models and image generation is stored locally to enforce fair usage policies.

2. How We Use Your Information

We use the information we collect to:

Provide and maintain our Service
Improve and personalize your experience
Communicate with you about updates and features
Ensure the security and integrity of our Service

3. Data Storage and Security

Your data is stored locally on your device using secure, industry-standard encryption. We do not have access to your personal information unless you explicitly choose to share it through cloud features.

4. Third-Party Services

Alevio may integrate with third-party AI services for enhanced functionality. When using these features, only the necessary data is transmitted to provide the service. We carefully select partners who share our commitment to privacy.

Cloud Services: When you use cloud-based AI models (such as GPT-4o, Claude, or other cloud providers), your messages and uploaded images are sent to these services for processing. We use secure API connections and do not store your data on our servers.
Image Generation: When using DALL-E image generation, your text prompts are sent to OpenAI's servers to generate images. Generated images are returned to your device and stored locally.
Web Search: When using web search features, your search queries are sent to our search partners to retrieve relevant information. Search results are processed and returned to your device.
Apple Shortcuts: When using Apple Shortcuts integration, your device's Shortcuts app may access Alevio through URL schemes. This integration is handled entirely by your device's operating system.

5. Your Rights

You have the right to:

Access your personal data stored on your device
Delete your data at any time through the app settings
Opt out of cloud features and keep all data local
Contact us with any privacy concerns

6. Changes to This Policy

We may update this Privacy Policy from time to time. We will notify you of any changes by posting the new Privacy Policy on this page and updating the "Last Updated" date.

7. Contact Us

If you have any questions about this Privacy Policy or our privacy practices, please contact us at:

privacy.alevio@gmail.com

Callbacks

A callback is a function passed as an argument to another function, which is then executed after the completion of an operation.

Example of a Callback Function

function fetchData(callback) {
  setTimeout(() => {
    console.log("Data fetched");
    callback();
  }, 2000);
}
  
function processData() {
  console.log("Processing data...");
}
  
fetchData(processData);

fetchData simulates an asynchronous operation using setTimeout.

processData is executed after fetchData completes.

Promises

A promise represents a future value and has three states:

Pending – Initial state, operation in progress.
Fulfilled – Operation completed successfully.
Rejected – Operation failed.

Creating a Promise

let fetchData = new Promise((resolve, reject) => {
  setTimeout(() => {
    let success = true; // Change to false to test rejection
    if (success) {
      resolve("Data received");
        } else {
      reject("Error fetching data");
    }
  }, 2000);
});
  
fetchData
  .then(result => console.log(result)) // Executes if resolved
  .catch(error => console.log(error)) // Executes if rejected
.finally(() => console.log("Operation complete"));

.then() runs when the promise is resolved.

.catch() runs when the promise is rejected.

.finally() runs regardless of success or failure.

Conclusion

Asynchronous programming allows JavaScript to handle time-consuming operations efficiently. Callbacks, promises, and async/await help manage asynchronous workflows. The next section will explore DOM manipulation, which enables JavaScript to interact with web pages dynamically.