Thread by @swapnakpanda

JavaScript Arrays[] Interview Questions 💙

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Before proceeding, do check the previous one of this series 👇

https://twitter.com/swapnakpanda/status/1459388854704558080?s=20

Disclaimer:

• The questions covered here are mostly conceptual
• I do not claim only these type of questions are/should be asked during interviews
• For interviews, you should have fundamentals strong. And you should be able to provide solutions to practical problems.

Series: 4️⃣
Level: Beginner
Topics:

1️⃣ Basics
2️⃣ Properties
3️⃣ Methods
4️⃣ Looping
5️⃣ Operators
6️⃣ Common Operations
7️⃣ Comparison

1️⃣ Basics

✪ What is an Array?
✪ What is Array Literal?
✪ Explain about indexes and negative indexes in an Array?
✪ What does typeof return for an array?
✪ What is an Array-Like object? Give some examples.
✪ What operations of an Array can be done on an Array-Like object?

2️⃣ Properties

✪ How to find size of an array?
✪ How to create an Array of a given size?
✪ Is array in JavaScript static sized or, dynamic sized?
✪ Is "length" a mutable property?/Can "length" of an Array be changed manually?

✪ What does happen when "length" is reduced?
✪ What will happen when "length" is increased?
✪ How to remove elements from the end of an array by manipulating the "length" property?

3️⃣ Methods

✪ Which methods of Array.prototype accepts negative indexes?
✪ How to do deep level flat operation?
✪ Which method will you use?
⇨ To find the first element of an array that matches a condition
⇨ To find if an array has an element that matches a condition

⇨ To fetch an element using negative index
⇨ To insert multiple elements at the end of an array
⇨ To insert multiple elements at the starting of an array
⇨ To remove multiple elements at the starting of an array
⇨ To remove multiple elements at the end of an array

⇨ To insert multiple elements at an index after removing multiple elements from the same index
⇨ To populate all indexes with the same value
⇨ To retrieve a sub-array from an index to an index
⇨ To copy an array
⇨ To convert an array-like object to array

4️⃣ Looping

✪ Between for...in and for...of, which is more suitable for an Array to loop through?
✪ Mention all Array.prototype methods which loop through the array.
✪ Can you loop an array which is just created using Array(n)?

5️⃣ Operators

✪ What is destructuring assignment for arrays?
✪ What is rest parameter inside destructuring assignment?
✪ Which is valid? [a, b, ...c], [a, ...b, c]
✪ Explain how spread operator operates.
✪ Swap 2 numbers using Array Destructuring.

6️⃣ Common Operations

✪ Insert an element into an array at starting/ending/any position by not mutating the original.
✪ Update an element of an array at starting/ending/any position by not mutating the original.

✪ Delete an element from an array at starting/ending/any position by not mutating the original.
✪ Insert and delete an element into/from an array at starting/ending/any position by using splice()
✪ Create a copy of an array using spread operator syntax.

✪ Merge 2 or, more arrays using concat()
✪ Merge 2 or, more arrays using spread operator syntax
✪ Find sum of all elements in an array using reduce()
✪ Shuffle elements of an array.
✪ Sort elements of an array using a custom defined order.

7️⃣ Comparison

✪ Mention the difference between

⇨ "Array()" and "new Array()"
⇨ Single parameter Array() and Multiple parameter Array()
⇨ Array.of() and Array.from()
⇨ find() and filter()
⇨ findIndex() and indexOf()
⇨ includes() and some()
⇨ some() and every()

⇨ map() and flatMap()
⇨ slice() and splice()
⇨ forEach() and map()
⇨ forEach() and for...of
⇨ shift() and pop()
⇨ unshift() and push()
⇨ reduce() and reduceRight()

The next 🧵 of this series will provide questions from

1️⃣ String

In addition to JavaScript, I have shared Interview Questions on few other subjects (SQL, DSA, Python, HTML, React, GIT) More coming in future.

For your convenience, I organised all these questions 🧵 in a "Twitter Moment". If you are interested, check 👇

twitter.com/i/events/14559…