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Cintra Software and Services Interview Questions and Answers
Q1. What are the different component lifecycles in react
React has several component lifecycles, including mounting, updating, and unmounting.
Mounting: when a component is being created and inserted into the DOM
Updating: when a component is being re-rendered due to changes in props or state
Unmounting: when a component is being removed from the DOM
Q2. What are the different CSS position properties
CSS position properties determine how an element is positioned on a web page.
static: default position, elements flow in document order
relative: positioned relative to its normal position
absolute: positioned relative to its nearest positioned ancestor
fixed: positioned relative to the browser window
sticky: positioned based on scroll position
Q3. How will improve the api latency of a system
To improve API latency, optimize database queries, use caching, implement load balancing, and optimize code.
Optimize database queries by using indexes, reducing unnecessary joins, and optimizing query execution plans.
Implement caching to store frequently accessed data in memory, reducing the need for repeated database queries.
Use load balancing to distribute incoming requests across multiple servers, preventing any single server from becoming overwhelmed.
Optimize code by iden...read more
Q4. What is the use of ref in react
Ref is used in React to access and manipulate the DOM directly.
Ref provides a way to access and modify DOM elements or React components.
It is commonly used for focusing input fields, triggering animations, or integrating with third-party libraries.
Ref can be created using the useRef() hook or by using the ref attribute in class components.
Example: const inputRef = useRef();
Example: const buttonRef = React.createRef();
Q5. How will you improve the db performanc
To improve db performance, optimize queries, use indexing, cache data, and scale horizontally.
Optimize queries by using appropriate indexes and avoiding unnecessary joins
Cache frequently accessed data to reduce database load
Scale horizontally by distributing the database across multiple servers
Use database monitoring tools to identify and resolve performance bottlenecks
Q6. What is CDN and list its uses
CDN stands for Content Delivery Network. It is a distributed network of servers that helps deliver web content efficiently.
CDN improves website performance by caching content closer to the user
It reduces latency and improves page load times
CDN helps handle high traffic loads and prevents server overload
It provides global coverage and ensures content availability worldwide
CDN can deliver various types of content like images, videos, scripts, etc.
Popular CDN providers include C...read more
Q7. How JS handles hoisting
JS hoisting is a mechanism where variable and function declarations are moved to the top of their scope during compilation.
Variable declarations are hoisted but not their initializations.
Function declarations are fully hoisted, including their definitions.
Hoisting can lead to unexpected behavior if not understood properly.
Example: console.log(x); var x = 5; // Output: undefined
Q8. What is closure
Closure is a feature in programming languages that allows a function to access variables from its outer scope even after it has finished executing.
Closure is created when a nested function references variables from its parent function.
It allows for data encapsulation and privacy in JavaScript.
Closures are commonly used in event handlers, callbacks, and asynchronous programming.
They can be used to create private variables and functions in object-oriented programming.
Closures c...read more
Q9. Design the DB for slack
Designing the database for Slack
Create tables for users, channels, messages, and teams
Use foreign keys to establish relationships between tables
Include columns for user details, channel details, message content, and timestamps
Consider indexing frequently queried columns for performance optimization
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