Junior DPS Interview Questions and Answers

Q1. Difference between var, let, const.
Ans. 
var, let, and const are all used to declare variables in JavaScript, but they have different scoping rules and behaviors.
• var has function scope and can be redeclared and reassigned

• let has block scope and can be reassigned but not redeclared

• const has block scope and cannot be reassigned or redeclared

• Use const for values that won't change, let for values that will, and avoid var
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Q2. Explain CSS box model. Do padding and margin apply to inline elements?
Ans. 
CSS box model defines the layout of elements on a webpage. Padding and margin can apply to block-level elements but not to inline elements.
• CSS box model consists of content, padding, border, and margin around an element.

• Padding adds space inside the border of an element.

• Margin adds space outside the border of an element.

• Padding and margin can apply to block-level elements like <div> but not to inline elements lik
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Q3. Difference between arrow functions and regular ones.
Ans. 
Arrow functions are shorter syntax for writing function expressions.
• Arrow functions do not have their own 'this' keyword.

• Arrow functions cannot be used as constructors.

• Arrow functions do not have the 'arguments' object.

• Arrow functions are more concise and easier to read.

• Regular functions are better for methods and constructors.
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Q4. How does JavaScript asynchronous model work
Ans. 
JavaScript asynchronous model allows non-blocking code execution by using callbacks and promises.
• JavaScript uses an event loop to handle asynchronous operations.

• Callbacks are functions passed as arguments to other functions and executed when the operation is complete.

• Promises are objects that represent the eventual completion or failure of an asynchronous operation.

• Async/await is a newer syntax that allows writing asyn...read more
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Round duration - 40 minutes
Round difficulty - Medium

Round duration - 15 minutes
Round difficulty - Easy

Q1. 
Count Subsequences Problem Statement
Given an integer array ARR of size N, your task is to find the total number of subsequences in which all elements are equal.
Explanation:
A subsequence of an array i...read more
Ans. 
The task is to count the number of subsequences in an array where all elements are equal.
• Iterate through the array and count the frequency of each element.

• For each element, calculate the number of subsequences using the formula (2^frequency - 1).

• Multiply the counts for each element to get the total number of subsequences.

• Print the result modulo 10^9 + 7.
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