Spinny Front end Developer Interview Questions and Answers

1 Hr coding round, Leetcode medium problems like Minimum Grid sum & Basic calculator

Q1. Max sum path in tree
Ans. 
Find the maximum sum path in a tree from root to leaf node.
• Start from the root node and traverse down to leaf nodes, keeping track of the sum at each node.

• At each node, compare the sum of the current path with the maximum sum found so far.

• Choose the path with the maximum sum as the final result.
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Q2. Array 2 sum problem
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Q1. React: Create a Timer
Ans. 
Create a simple timer using React
• Use state to store the timer value

• Use setInterval to update the timer every second

• Display the timer value in the component's render method
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Q2. Javascript: implement Debounce
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Q1. What do you know about the company + common behaviour question
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Q2. About roles in previous org
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Round duration - 60 Minutes
Round difficulty - Medium

Mostly focused on Data Structure & Algorithm

Q1. Rotate Linked List
You have been given a Linked List having ‘N’ nodes and an integer ‘K’. You have to rotate the Linked List by ‘K’ positions in a clockwise direction.
Example :
 Given Linked List : 1 2...read more
Ans. Brute Force
Find the length of the Linked List to check whether the ‘K’ is greater than the Length of the Linked List or not. Take a modulo of ‘K’ with its length if it is greater than the length. Reach the (‘K’+1)th node from last and change the pointers of nodes to get a rotated Linked List.
 
Here is the algorithm:
 
1. Base Condition : If ‘HEAD’ is equal to ‘NULL’ or ‘K’ is equal to 0, then return ‘HEAD’ of the L...read more
Answered by CodingNinjas
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Q2. Reverse the order of words in a string
You are given a string ‘STR’ containing space-separated words. A word is a sequence of non-space characters. Your task is to reverse the order of words in ‘STR’.
No...read more
Ans. Convert to an array of words
Use an array ‘ARR’ to store the words in ‘STR’. Traverse the string ‘STR’ and append each word at the end of ‘ARR’. Use the string ‘RES’ to store the answer. Traverse the array ‘ARR’ in reverse and append the words in ‘ARR’ to ‘RES’ followed by a whitespace character.
 
• Create an empty array of string ‘ARR’.
• Initialize an empty string ‘CUR_STR’. Use it to store a single word from ‘STR’.
• Run...read more
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Round duration - 50 Minutes
Round difficulty - Medium

JavaScript core concepts with some examples and problem discussion

Q1. Javascript Questions
1) What is currying in Javascript?
2) Explain hoisting with a code snippet.
3) What does this return (typeof null) ?
4) What is callback hell?
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Round duration - 30 Minutes
Round difficulty - Easy

Q1. Basic HR Questions
Why should we hire you?
What keeps you motivated?
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Q1. Polyfill for bind Closures Call apply bind let const var lexical environment scope output questions
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Q1. What is bind in javascript and write its polyfill
Ans. 
Bind creates a new function with a specified 'this' value and arguments.
• Bind returns a new function with the same body as the original function.

• The 'this' value of the new function is bound to the first argument passed to bind().

• The subsequent arguments are passed as arguments to the new function.

• Polyfill for bind() can be created using call() or apply() methods.
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Q2. Output questions related to hoisting and closures.
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Q3. What is event bubbling, event capturing and its use?
Ans. 
Event bubbling and event capturing are two mechanisms in JavaScript that describe the order in which events are handled.
• Event bubbling is the process where an event is first captured by the innermost element and then propagated to its parent elements.

• Event capturing is the opposite process where an event is first captured by the outermost element and then propagated to its child elements.

• Event bubbling is the default b...read more
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Q4. What is the difference between async and defer
Ans. 
async loads script while page continues to load, defer loads script after page has loaded
• async loads scripts asynchronously while page continues to load

• defer loads scripts after the page has loaded

• async scripts may not execute in order, while defer scripts do

• async scripts may cause rendering issues, while defer scripts do not
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Q5. Explain box model in css, and what is specificity in CSS. What are render-blocking statements?
Ans. 
Box model defines how elements are rendered in CSS. Specificity determines which CSS rule applies to an element. Render-blocking statements delay page rendering.
• Box model includes content, padding, border, and margin.

• Specificity is calculated based on the number of selectors and their types.

• Render-blocking statements are CSS or JavaScript files that prevent the page from rendering until they are loaded.

• Use media querie...read more
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Q6. Tell about Saas( Syntactically Awesome Style Sheets)
Ans. 
Saas is a CSS preprocessor that extends the functionality of CSS with variables, mixins, and more.
• Saas stands for Syntactically Awesome Style Sheets

• It allows for the use of variables, mixins, and functions in CSS

• Saas code must be compiled into CSS before it can be used in a web page

• Saas is often used in conjunction with build tools like Gulp or Webpack
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Q1. Write code to find if two objects are equal or not in javascript
Ans. 
Code to check equality of two objects in JavaScript
• Use the JSON.stringify() method to convert the objects into strings

• Compare the string representations of the objects using the === operator

• If the strings are equal, the objects are considered equal
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Q2. Write a code to find if the input date is today or tomorrow based on the current date. If it's not today or tomorrow, output the no of days difference between the input date and the current date.
Ans. 
Code to find if input date is today/tomorrow or no of days difference from current date.
• Get current date using Date() constructor

• Convert input date to Date object

• Compare input date with current date to check if it's today/tomorrow

• If not, calculate the difference in days using getTime() method

• Output the result accordingly
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Q3. Some output questions based on promises.
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Q4. How will you implement infinite scrolling in react js?
Ans. 
Implement infinite scrolling in React JS using Intersection Observer API.
• Use Intersection Observer API to detect when the user has scrolled to the bottom of the page.

• Fetch new data and append it to the existing data using setState.

• Use a loading spinner to indicate that new data is being fetched.

• Add a debounce function to prevent multiple API calls while scrolling.

• Use a key prop when rendering the list of data to avoid
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Question are very tough and faad

Question like trees linked list and graphs

1 Hr coding round, Leetcode medium problems like Minimum Grid sum & Basic calculator