Fueling Curiosity, One Insight at a Time

Typescript as const turns everything into readonly.

const user = {
  role: 'admin',
} as const;

user.role = 'editor'; // ❌ Error: Cannot assign to 'role' because it is a read-only property.

💡 as const is great for making values literal and immutable — useful in Redux, Enums, etc.

#Typescript #CCT1JMA0Z

JavaScript: Object.groupBy()

Grouping data used to be messy — relying on Array.reduce() with verbose logic. But JavaScript's new Object.groupBy() method has made things incredibly elegant and easy!

With just one line, you can group array items based on any property.
It’s clean, readable, and production-friendly.

📌 Example:

const products = [
  { name: "T-shirt", category: "clothes", price: 50 },
  { name: "Apple", category: "food", price: 5 },
  { name: "Shoes", category: "clothes", price: 35 },
  { name: "Orange", category: "food", price: 7.5 },
  { name: "Blueberry", category: "food", price: 4.5 }
];

const grouped = Object.groupBy(products, product => product.category);

console.log(grouped);

💡 Output:

{
  clothes: [
    { name: "T-shirt", category: "clothes", price: 50 },
    { name: "Shoes", category: "clothes", price: 35 }
  ],
  food: [
    { name: "Apple", category: "food", price: 5 },
    { name: "Orange", category: "food", price: 7.5 },
    { name: "Blueberry", category: "food", price: 4.5 }
  ]
}

✅ Cleaner. ✅ Less boilerplate. ✅ Much easier to read.

#CCT1JMA0Z #WebDevelopment

Using Makefile for tedious commands

A Makefile can be used to automate a commands, simplifying the execution process. Here’s a concise example:

.PHONY: run-script

# Target to run a long command
run-script:
    @echo "Running a long command..."
    sleep 5  # Simulate a long-running command
    @echo "Command completed."

Running the Makefile
1. Create a Makefile: Save the above content as Makefile in your project directory.
2. Run Make: In your terminal, navigate to the project directory and execute:

make run-script

Benefits
• Simplicity: Easily run a long command without remembering the syntax.
• Automation: Reduces manual effort and potential errors.
#cli #automation #makefile #commands

💡 Why is [] == ![] true in JavaScript?

It all comes down to type coercion and how JavaScript evaluates expressions using the == (abstract equality) operator.

Here’s the breakdown:
![] evaluates to false because an empty array is truthy, and the ! operator negates it.
So the expression becomes: [] == false
When comparing an object (like[]) to a boolean with==, JavaScript converts both sides to numbers:
+[] → 0
+false → 0
So:

[] == ![]  
=> [] == false  
=> +[] == +false  
=> 0 == 0  
=> true

✅ Hence, [] == ![] evaluates to true.

#CCT1JMA0Z

How Dependency Injection Works in NestJS

NestJS uses Dependency Injection (DI) to manage the creation and lifecycle of classes like services, repositories, and providers. It leverages TypeScript's metadata to resolve dependencies automatically.

🚀 How It Works:

• Declare Providers: Services and other classes are marked with @Injectable() to make them available for dependency injection. They are then registered as providers in a module.

// user.service.ts
@Injectable()
export class UserService {
  getUsers() {
    return ['Alice', 'Bob'];
  }
}

• Register Providers in a Module

// user.module.ts
@Module({
  controllers: [UserController],
  providers: [UserService],
})
export class UserModule {}

• Use the Service via Constructor Injection

// user.controller.ts
@Controller('users')
export class UserController {
  constructor(private readonly userService: UserService) {}

  @Get()
  findAll() {
    return this.userService.getUsers();
  }
}

NestJS reads the constructor types and injects the required instances for you. No manual instantiation needed!

✅ Benefits:
• Decouples components
• Simplifies testing with mocks
• Promotes cleaner, modular code

#nestjs #dependencyinjection #typescript

How to Revoke and Amend the Most Recent Git Commit Message.
To undo the most recent commit, unstage the changes, and update the commit message, follow these steps:

1. Revoke the latest commit and unstage the changes.
git reset HEAD~1

2. Stage the changes again.
git add .

3. Create a new commit with the updated message
git commit -m "New commit message"
(If you just want to change the previous commit message) - git commit --amend

4. Force-push the new commit to the remote repository
git push origin <branch-name> --force

> ⚠️ Use --force cautiously, especially on shared branches, as it rewrites history.

pgvector provides native support for vector similarity search in PostgreSQL. It supports three types of distance metrics, each useful depending on the use case:
• <=> Cosine distance – Measures the angle between two vectors (ignores magnitude). Great for comparing meaning in text (e.g., NLP). Smaller angle = more similar.
• <#> L2 (Euclidean distance) – Measures the straight-line distance between two vectors. Takes both direction and size into account. Good when actual value differences matter (like in image or audio data).
• <-> Inner product – Measures how much two vectors point in the same direction and how large they are. If vectors are normalized (length = 1), it works like cosine similarity. Great for ranking similarity when vectors are preprocessed.

#pgvector #PostgreSQL #VectorSearch #Embeddings

ClickHouse DB

It is a column-oriented database management system designed for online analytical processing (OLAP). It's optimised for real-time analytics on large volumes of data and is known for being fast, highly scalable, and efficient for read-heavy workloads like metrics, logs, events, and other analytical data.

Key features are -
1. Columnar storage : Stores data by columns instead of rows, enabling efficient compression and faster reads.
2. Works super fast : Designed to process billions of rows per second per server.
3. SQL-compatible.
4. Materialized views : For real-time aggregation and data transformation.
#databases #click_house_db #analytics

Validating date and time field in Rails

validates_timeliness gem helps us to check if a date or time field is valid and meets certain conditions — like being in the past, in the future, or within a specific range. It can do following things.
1. Check if a date is valid (e.g., "2025-02-30" is not a valid date).
2. Make sure a date is before or after a certain time as needed.
3. Restrict a field to only accept dates, times or datetimes.
4. Works well with user input in different formats.
For example :

class Event < ApplicationRecord
  validates_timeliness :start_time, on_or_after: :now, type: :datetime
end

This makes sure start_time is not in the past.

#CU6U0R822 #date_time_validation

friendly_id is a Rails gem that lets you use secure, human-readable slugs instead of record IDs in URLs.
https://github.com/norman/friendly_id
it updates the url
from this :

https://localhost:3000/employer/job_posts/2/job_applications/new

to this:

https://localhost:3000/employer/job_posts/frontend-developer-37b70ea4-761e-4369-832e-f5b373f7f00b/job_applications/new

#CU6U0R822