Fueling Curiosity, One Insight at a Time

Picture-in-Picture (PiP) API – Enabling Floating Video Playback

The Picture-in-Picture (PiP) API enables developers to present an HTML <video> element in a small, floating, always-on-top window. This allows users to continue watching a video while interacting with other applications or browser tabs.

How to use it (basic example):

html

<video id="myVideo" src="video.mp4" controls></video>
<button id="pipButton">Enter PiP</button>

js

const video = document.getElementById('myVideo');
const button = document.getElementById('pipButton');

button.addEventListener('click', async () => {
  try {
    if (document.pictureInPictureElement) {
      await document.exitPictureInPicture();
    } else {
      await video.requestPictureInPicture();
    }
  } catch (err) {
    console.error(`Failed to toggle PiP: ${err}`);
  }
});

Key Concepts
• video.requestPictureInPicture(): Initiates PiP mode for the video element.
• document.exitPictureInPicture() : Exits PiP mode.
• document.pictureInPictureElement : Returns the element currently in PiP, or null.
• Associated Events:
◦ enterpictureinpicture
◦ leavepictureinpicture

video.addEventListener('enterpictureinpicture', () => {
  console.log('Video entered PiP mode');
});

video.addEventListener('leavepictureinpicture', () => {
  console.log('Video left PiP mode');
});

⚠️ Limitations
• Only applicable to native <video> elements.
• Most browsers require the video to be playing before entering PiP.
• Must be triggered through a user gesture (e.g., a click).
• Safari has limited support and relies on its own implementation.
🌐 Browser Support
• Chrome
• Edge
• Opera
• Firefox (with some restrictions)
#CCT1JMA0Z

File Preview in React — Beyond Just Images
Building a file preview system in React can surface several helpful patterns — especially when working with images, PDFs, media, and plain text files.

• You can preview any local file before upload using:

URL.createObjectURL(file)

It works seamlessly with:
• Images
• PDFs
• Audio files
• Videos
• Plain text
Tip: Always call URL.revokeObjectURL() when the preview is no longer needed to prevent memory leaks.

🔄 Handling Local and Server Files Together
To support previews for both uploaded and already-stored files, use a union type:

// Local preview
{ isLocal: true, file: File }

// Server-hosted file
{ url: '/api/files/:id', name: string, type: string }

Then render conditionally based on file.type. Rendering Previews Based on File Type
• <img> → for images
• <iframe> → for PDFs or text files
• <audio> / <video> → for media files
#CCT1JMA0Z #react

📌 Using Alpine.js in Rails to Toggle Content Efficiently

You can use Alpine.js in a Rails app to handle simple UI interactions like showing, hiding, or toggling content — with zero overhead and great maintainability.

🧠 How it works:
• Alpine adds lightweight reactivity directly in your HTML using attributes like x-data, @click, and x-show.
• Clicking a button updates the type (or any reactive) value.
• Alpine automatically re-evaluates all x-show (and related) bindings when that reactive value changes.
• It then updates the UI by toggling styles like display: none, not by re-rendering or manipulating the DOM.
• On clicking the "Urgent" button, Alpine applies display: none to the normal_partial and removes it from urgent_partial, effectively toggling visibility between the two.
💡 Example in Rails ERB:

<div x-data="{ type: 'normal' }">
  <button @click="type = 'normal'">Normal</button>
  <button @click="type = 'urgent'">Urgent</button>

  <div x-show="type === 'normal'">
    <%= render "normal_partial" %>
  </div>

  <div x-show="type === 'urgent'">
    <%= render "urgent_partial" %>
  </div>
</div>

• Both partials are rendered server-side on initial load
• Alpine just toggles their visibility using CSS (e.g., display: none), it wont manipulate DOM.
• No data loss or performance bottleneck — ideal for UI tab switching or inline modals
✅ Why it's great:
• No page reloads or re-renders
• No JavaScript DOM manipulation — just CSS toggling
• Preserves state and DOM structure
• Ideal for tabs, modals, section toggles, and lightweight UI
#Rails #Alphine.js

Creating Google Calendar Events with NestJS

Integrating Google Calendar event creation in a NestJS backend can be done seamlessly using the googleapis package.
Key Steps:
• Set up OAuth2 with access and refresh tokens.
• Use calendar.events.insert() to create events.
• Always include the timeZone field to ensure accurate scheduling.
Sample code:

const event = {
  summary: 'Team Sync',
  start: { dateTime: '2025-06-26T10:00:00+05:30', timeZone: 'Asia/Kolkata' },
  end: { dateTime: '2025-06-26T11:00:00+05:30', timeZone: 'Asia/Kolkata' },
};

await calendar.events.insert({
  calendarId: 'primary',
  requestBody: event,
});

Common Pitfalls:
• Incorrect scopes → leads to permission denied errors.
• Missing timeZone → causes unexpected event timings.
• Expired tokens → results in 401 Unauthorized errors.
#NestJS

Understanding ExecutionContext in NestJS Guards

Today I learned how ExecutionContext works in NestJS — it's a powerful tool for accessing low-level request details within Guards, Interceptors, and Custom Decorators.
While building a custom AuthGuard, I used ExecutionContext to extract the request object and retrieve the authenticated user like so:

import { CanActivate, ExecutionContext, Injectable } from '@nestjs/common';

@Injectable()
export class AuthGuard implements CanActivate {
  canActivate(context: ExecutionContext): boolean {
    const request = context.switchToHttp().getRequest();
    const user = request.user;

    return !!user; // or apply custom authorization logic
  }
}

Why It Matters:
• ExecutionContext wraps the current request lifecycle and gives you flexible access to request-specific information.
• You can switch between different transport layers (HTTP, RPC, WebSockets) using methods like switchToHttp(), switchToRpc(), etc.
• It's essential for building dynamic and context-aware logic in guards, interceptors, and decorators.
Pro Tip:
Use context.getClass() and context.getHandler() to access metadata about the controller and handler being executed — especially useful for implementing role-based access control or custom permission systems.

#CCT1JMA0Z #NestJS

the term Cannibalization in warehouse terms meaning taking components or parts from one unit (often damaged, unused, or scrapped) to use in repairing or completing another unit.
In simple terms we can understand it as refubrished items where later the warehouse can send that to a buyer and then the buyer decide which store to sell these items in a discounted price.

#warehouse #outbound

JavaScript Temporal — A Modern Approach to Date & Time

Today I explored the Temporal API in JavaScript — a long-awaited, modern alternative to the built-in Date object.
The traditional Date API is known for its limitations: it’s mutable, difficult to work with across time zones, and error-prone when performing date arithmetic. Temporal addresses these issues with a clean, consistent, and powerful API.

Key Advantages of Temporal
• Immutable: All Temporal objects are immutable, avoiding side effects
• Time zone-aware: Native support via ZonedDateTime
• Consistent parsing & formatting
• Clear duration handling with Temporal.Duration
• More intuitive syntax — no more 0-based months
Practical Examples

// Get current date-time
const now = Temporal.Now.plainDateTimeISO();
console.log(now.toLocaleString()); // "6/18/2025, 6:01:52 PM"

// Time zone conversion
const nyMeeting = Temporal.ZonedDateTime.from('2025-06-18T10:00[America/New_York]');
const kolkataTime = nyMeeting.withTimeZone('Asia/Kolkata');
console.log(kolkataTime.toLocaleString()); // "6/18/2025, 7:30:00 PM GMT+5:30"

Working with Durations

const start = Temporal.PlainDate.from('2025-01-01');
const end = Temporal.PlainDate.from('2025-06-18');
const diff = start.until(end);
console.log(diff.toLocaleString()); // "168 days"

Why This Matters ?
Whether you're building scheduling systems, handling international time zones, or performing complex date calculations — the Temporal API offers accuracy, clarity, and reliability that the current Date API lacks.

#CCT1JMA0Z

The difference between Active Model association call, joins and includes. Consider two tables: order_requests and orders, where each order_request has many orders.

1. order_request.orders
• Purpose: You’re accessing the associated orders from a single order_request object.
• Behavior: This will trigger a separate SQL query unless the association was already loaded (using includes).

SELECT "orders".* FROM "orders" WHERE "orders"."order_request_id" = 123;

• Use Case: When you’re working with one order_request and want to fetch its orders.

2. order_requests.joins(:orders)
• Purpose: Adds an INNER JOIN in the SQL between order_requests and orders.
• Behavior: Doesn't load orders into memory, just uses them for filtering or sorting in SQL.

SELECT "order_requests".* 
FROM "order_requests"
INNER JOIN "orders" ON "orders"."order_request_id" = "order_requests"."id";

• Use Case: When you want to query order_requests based on conditions in orders (e.g., where(orders: { status: 'active' })), but don’t need to access orders in Ruby.

3. order_requests.includes(:orders)
• Purpose: Performs eager loading via a LEFT OUTER JOIN + separate query, or just a separate query depending on ActiveRecord's optimization.
• Behavior: Loads orders for each order_request to prevent N+1 queries when looping.

SELECT "order_requests".* FROM "order_requests" WHERE ...
SELECT "orders".* FROM "orders" WHERE "order_request_id" IN (1, 2, 3, ...)

• Use Case: When you plan to access order_request.orders for many records in a loop and want to avoid repeated SQL calls (N+1 issue).

#Rails

How Decorators Work in NestJS

Decorators in NestJS are a powerful way to attach metadata to routes, classes, or parameters. Today, I implemented a custom @Roles() decorator to control access to certain routes based on user roles.

✨ Example:

✅ Custom Decorator: @Roles()

// roles.decorator.ts
import { SetMetadata } from '@nestjs/common';

export const Roles = (...roles: string[]) => SetMetadata('roles', roles);

This attaches metadata like roles = ['Admin'] to the route handler.

✅ Guard to Read Metadata

// roles.guard.ts
@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private reflector: Reflector) {}

  canActivate(context: ExecutionContext): boolean {
    const requiredRoles = this.reflector.get<string[]>(
      'roles',
      context.getHandler()
    );

    const request = context.switchToHttp().getRequest();
    const user = request.user;

    return requiredRoles?.includes(user?.role); // Check if user has the role
  }
}

✅ Controller Usage

@UseGuards(RolesGuard)
@Roles('Admin')
@Patch(':id')
updateOrg() {
  // This route is accessible only to users with the 'Admin' role
}

Under the hood, decorators use Reflect.defineMetadata to attach metadata, and NestJS’s Reflector service helps retrieve that metadata in guards or interceptors.

✅ Takeaway: Custom decorators make your code cleaner, declarative, and easier to manage — especially when dealing with role-based access in multi-user systems.

#typescript #NestJs

Using emit in NestJS

In NestJS, event-based communication can be implemented using @nestjs/event-emitter package, which is built on top of eventemitter2 . It's particularly useful for decoupling the parts of our application — for example, sending notifications, logging, or triggering async jobs after certain actions.

How to use it?

• Install the necessary package:

npm install --save @nestjs/event-emitter

• Register the module in the app:

// app.module.ts
import { EventEmitterModule } from '@nestjs/event-emitter';

@Module({
  imports: [
    EventEmitterModule.forRoot(),
  ],
})
export class AppModule {}

• Emit an event from anywhere in the app:

// user.service.ts
import { EventEmitter2 } from '@nestjs/event-emitter';

@Injectable()
export class UserService {
  constructor(private eventEmitter: EventEmitter2) {}

  async createUser(userDto: CreateUserDto) {
    const user = await this.userRepository.save(userDto);
    
    this.eventEmitter.emit('user.created', user); // 🔥

    return user;
  }
}

• Handle the event using a listener:

// user.listener.ts
import { OnEvent } from '@nestjs/event-emitter';

@Injectable()
export class UserListener {
  @OnEvent('user.created')
  handleUserCreatedEvent(payload: any) {
    console.log('User created!', payload);
    // Trigger welcome email, analytics, etc.
  }
}

Why use emits?

✅ Decouples the core logic from side-effects
✅ Makes it easier to add/remove behaviours like notifications, logging
✅ Encourages modular architecture

#CCT1JMA0Z #nestJs #event_based_communication