Backend and Frameworks

Table of Content

Web API

Web APIs (Application Programming Interfaces) provide built-in functionalities that allow JavaScript to interact with the browser and external services. This section covers key browser APIs, including LocalStorage, SessionStorage, Fetch API, and Geolocation API.

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

Local Storage and Session Storage

The Web Storage API allows storing key-value pairs in the browser.

Local Storage (Persistent Storage)

Data stored using localStorage persists even after the browser is closed.

Setting and Getting Data

// Store data
localStorage.setItem("username", "Alice");
  
// Retrieve data
let user = localStorage.getItem("username");
console.log(user); // Outputs: Alice

Removing Data

localStorage.removeItem("username"); // Removes a specific item
localStorage.clear(); // Clears all stored data

Session Storage (Temporary Storage)

Session storage works like local storage but clears data when the session (tab) is closed.

sessionStorage.setItem("sessionUser", "Bob");
console.log(sessionStorage.getItem("sessionUser"));
sessionStorage.removeItem("sessionUser");

Fetch API (Making HTTP Requests)

The Fetch API allows JavaScript to make network requests asynchronously, commonly used for retrieving data from APIs.

Fetching Data from an API

fetch("https://jsonplaceholder.typicode.com/users/1")
  .then(response => response.json()) // Convert response to JSON
  .then(data => console.log(data)) // Handle retrieved data
.catch(error => console.error("Error:", error)); // Handle errors

Using `async/await` for Fetch Requests

async function getUserData() {
  try {
    let response = await fetch("https://jsonplaceholder.typicode.com/users/1");
    let data = await response.json();
    console.log(data);
  } catch (error) {
    console.log("Error fetching data:", error);
  }
}
  
getUserData();

Sending Data Using POST Request

fetch("https://jsonplaceholder.typicode.com/posts", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ title: "New Post", body: "Post content", userId: 1 })
})
  .then(response => response.json())
  .then(data => console.log("Post created:", data))
  .catch(error => console.log("Error:", error));

Geolocation API (Getting User Location)

The Geolocation API retrieves the user's current location.

Checking if Geolocation is Supported

if ("geolocation" in navigator) {
  console.log("Geolocation is supported!");
} else {
  console.log("Geolocation is not supported.");
}

Getting User's Current Location

navigator.geolocation.getCurrentPosition(
  position => {
    console.log("Latitude:", position.coords.latitude);
    console.log("Longitude:", position.coords.longitude);
  },
  error => console.log("Error getting location:", error.message)
);

Tracking User Location in Real-Time

navigator.geolocation.watchPosition(
  position => {
    console.log("Updated Location:", position.coords.latitude, position.coords.longitude);
  }
);

Clipboard API (Copying and Pasting Data)

The Clipboard API allows copying and pasting text programmatically.

Copying Text to Clipboard

navigator.clipboard.writeText("Copied text!").then(() => {
  console.log("Text copied to clipboard!");
});

Reading Text from Clipboard

navigator.clipboard.readText().then(text => {
  console.log("Clipboard content:", text);
});

Notification API (Displaying Browser Notifications)

The Notification API allows web applications to send notifications to users.

Requesting Notification Permission

if (Notification.permission !== "granted") {
  Notification.requestPermission().then(permission => {
    console.log("Notification permission:", permission);
  });
}

Sending a Notification

new Notification("Hello!", {
  body: "This is a notification from JavaScript.",
  icon: "icon.png"
});

Intersection Observer API (Detecting Element Visibility)

The Intersection Observer API detects when an element enters or leaves the viewport, useful for lazy loading images or triggering animations.

let observer = new IntersectionObserver(entries => {
  entries.forEach(entry => {
    if (entry.isIntersecting) {
      console.log("Element is in view:", entry.target);
    }
  });
});
  
let targetElement = document.getElementById("observe-me");
observer.observe(targetElement);

Conclusion

Web APIs extend JavaScript's capabilities by enabling data storage, making HTTP requests, accessing user location, handling clipboard interactions, and displaying notifications. The next section will explore browser compatibility and performance optimization techniques to ensure smooth execution across different devices and environments.