How to REMOVE DUPLICATES from an array in JavaScript? (4 ways in under 9 mins!)
⏱Timestamps:
0:00 Intro
0:26 Set
01:10 Important Note
01:22 filter()
03:38 reduce()
05:11 For loop
08:19 outro
In this video, I’ve explained 4 different ways to remove duplicates from an array in JavaScript, step-by-step — a concept that every beginner or fresher preparing for JavaScript or frontend interviews must understand.
Removing duplicates is one of the most commonly asked questions in coding interviews. It not only tests your problem-solving skills, but also your understanding of JavaScript fundamentals, ES6 features, and array methods.
That’s why I decided to go beyond just one solution and show you four different approaches — from the modern, clean ones to the more logical, hands-on ones.
Here’s what we’ll cover in detail :
1. Using Set
The Set object in JavaScript automatically stores unique values.
By converting your array into a Set and spreading it back into a new array, you can remove all duplicates with a single line of code.
This is the simplest and most efficient ES6-based approach, ideal for beginners learning modern JavaScript.
const uniqueValues = [...new Set(arr)];
2. Using filter()
The filter() method allows you to create a new array that passes a certain condition.
Here, we check if the current index of an element matches the first occurrence index (arr.indexOf(item)), which ensures duplicates are skipped.
This approach teaches how higher-order functions work and how to apply logic using built-in methods.
3. Using reduce()
The reduce() method is perfect to demonstrate the accumulator pattern.
In this solution, we loop through each element and manually accumulate only unique values by checking if they already exist in the array.
It’s a great example of how you can use functional programming to build logic without using loops.
4. Using for loop
The classic for loop approach helps beginners understand the manual logic behind removing duplicates.
It uses nested loops to compare each element and track if it’s already been added to the uniqueValues array.
Though not the most efficient, this method strengthens your grasp of core JavaScript logic and array iteration.
💡 Why You Should Watch This Video
✅ Perfect for JavaScript interview preparation
✅ Ideal for freshers and beginners learning ES6 concepts
✅ Learn four different ways to solve the same problem — a big plus for interviews
✅ Strengthen your understanding of Set, filter(), reduce(), and loops
✅ Build confidence in explaining your approach during interviews
Whether you’re revising core JavaScript, brushing up for a coding round, or improving your problem-solving mindset, this video will give you a complete understanding of how to remove duplicates in multiple ways — each with its own logic, pros, and learning value.
If this video helps you, make sure to like 👍, comment 💬, and subscribe 🔔 for more in-depth explanations on JavaScript concepts, frontend interview questions, and real-world coding tips.
Master map(), filter() and reduce() in 13 mins!👨💻🚀: • Master map(), filter() and reduce() in 13 ...
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