Question 1

How do you create a REST API using Node.js? Provide a simple example with GET and POST methods.

Accepted Answer

Creating a REST API in Node.js typically involves using the Express framework, which simplifies routing and middleware management. Below is an example of a simple REST API that handles GET and POST requests:

1. First, ensure you have Node.js and Express installed:
   ```bash
   npm install express body-parser
   ```

2. Create a file named `app.js` with the following code:
   ```javascript
   const express = require('express');
   const bodyParser = require('body-parser');

const app = express();
   app.use(bodyParser.json());

let items = [];

// GET method to retrieve items
   app.get('/api/items', (req, res) => {
       res.json(items);
   });

// POST method to add a new item
   app.post('/api/items', (req, res) => {
       const newItem = req.body;
       items.push(newItem);
       res.status(201).json(newItem);
   });

const PORT = process.env.PORT || 3000;
   app.listen(PORT, () => {
       console.log(`Server is running on port ${PORT}`);
   });
   ```

In this example, we have two endpoints: one for retrieving items and another for adding new items. The `body-parser` middleware is used to parse JSON payloads. When a new item is posted, it is added to the `items` array, and the newly created item is returned with a status of 201. This shows how to set up a basic RESTful API using Node.js.

Question 2

What is a RESTful API?

Accepted Answer

'REST stands for Representational State Transfer. A RESTful API is an architectural style for designing networked applications. It relies on stateless, client-server communication and uses standard HTTP methods like GET, POST, PUT, and DELETE to interact with resources identified by URIs.'

Tip: Mention statelessness and standard HTTP methods.

Question 3

What is the JavaScript execution context, and how do closures work in relation to it? Provide an example in a React context.

Accepted Answer

In JavaScript, the execution context is an abstract concept that holds information about the environment within which the current code is being executed. It consists of the variable scope, the value of `this`, and the line of code currently being executed. Closures are a feature in JavaScript where an inner function has access to the outer function's variables even after the outer function has finished executing. This is especially useful in React for preserving state or creating event handlers. Here's an example demonstrating closures in a React component: ```javascript import React, { useState } from 'react'; const Counter = () => { const [count, setCount] = useState(0); const increment = () => { setCount(prevCount => prevCount + 1); }; return (

Count: {count}

); }; export default Counter; ``` In this example, the `increment` function forms a closure around the `count` state variable. Even after the `Counter` component re-renders, `increment` still has access to the latest value of `count`. This illustrates how closures can maintain state in React components effectively.

Question 4

What is the AWS Cloud system design interview process like?

Accepted Answer

The AWS Cloud system design interview generally involves several key elements:

1. Understanding Requirements: You will be asked to clarify the requirements of the system you need to design. This could include scalability, availability, and latency requirements. For example, "Design a scalable URL shortening service."

2. High-Level Architecture: You should outline the components involved, such as using AWS services like API Gateway, Lambda, DynamoDB, and S3. A diagram can be helpful here:
   - API Gateway: Entry point for HTTP requests.
   - Lambda: Business logic for creating and retrieving URLs.
   - DynamoDB: Storing URL mappings.
   - S3: Static content storage if needed.

3. Detailed Component Design: Dive deeper into each component. For example, for DynamoDB, discuss table design, partition keys, and indexing strategies:
   ```json
   {
       "TableName": "URLMappings",
       "KeySchema": [
           {"AttributeName": "shortUrl", "KeyType": "HASH"}
       ],
       "AttributeDefinitions": [
           {"AttributeName": "shortUrl", "AttributeType": "S"}
       ]
   }
   ```

4. Scalability and Reliability: Discuss how you would handle increased load and ensure high availability. Mention AWS features like Auto Scaling, Load Balancers, and Multi-AZ deployments.

5. Cost Considerations: Be prepared to talk about cost-effectiveness. Discuss how using serverless architecture can reduce costs compared to traditional servers.

This process evaluates your critical thinking, technical knowledge, and ability to design robust systems.

Question 5

How many times should you follow up with a prospect?

Accepted Answer

'Persistence is key in sales. Statistics show that most sales are made after the 5th to 8th touchpoint. I will follow up consistently using different channels (email, phone, LinkedIn) until I get a definitive 'Yes' or 'No', while ensuring my follow-ups add value rather than just being annoying.'

Tip: Emphasize persistence and adding value in every follow-up.

SarthiQ

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