NodeJs

Question 1

what’s compiled binary file in nodejs, how to do that?

Answer 1

• create a standalone, self-contained binary from your JavaScript or TypeScript source code
• without needing to install npm/Deno or dependencies
• achieve faster startup time

deno compile
nexe or pkg do for Node

Question 2

Event loop in Nodejs

Answer 2

• is used by NodeJs for async actions
• it uses threads within libuv
• for io-bound operations
• event loop gets initiated inside the main thread
• root code executed before event loop
• each cycle of event loop is called a Tick

Question 3

5 phases of event loops

Answer 3

1. Timers
2. I/O logic
3. Polling
4. Check
5. Close

Question 4

What’s the Microtasks ?

Answer 4

immidate tasks
These are executed after each phase of the event loop. This is where promises are executed.

• process.nextTick()
• promise.then()

Question 5

setTimeout vs. setImmediate

Answer 5

The “setTimeout” function in Node.js is commonly used to schedule functions to be executed after a certain amount of time.

“setImmediate” functions are executed before any pending “setTimeout” callbacks, I/O callbacks

Question 6

Helmet is a Node.js?

Answer 6

It helps protect web applications from a variety of common security vulnerabilities, such as cross-site scripting (XSS), clickjacking, and more.

Question 7

Morgan Middleware in nodejs ?

Answer 7

Morgan is a popular logging middleware for Node.js applications. It is used to log HTTP requests and responses in a structured format, making it easier to monitor and debug web server activity.

Question 9

Why using classes for defining DTO instead of interfaces in NestJs?

Answer 9

• interfaces are a part of TS and are not preserved post-compilation
• classes allow to do more
• NestJs cannot refer to interfaces in run-time

Question 10

Decorator vs decorator factory in typescript

Answer 10

In TypeScript, decorators are a way to add metadata to classes, methods, or properties.

• Decorator: Applied directly to the target without parameters.
• Decorator Factory: Used to create decorators with parameters or to customize the behavior of the decorator.