JavaScript Arrays Explained In-Depth | Javascript Full Course #07

Ready to master the most powerful and versatile data structure in JavaScript? In this complete, in-depth guide, we will explore everything you need to know about JavaScript Arrays, from the absolute basics to the advanced, modern techniques used by professional developers.
We start from "first principles," explaining what an array is and how to create and access its elements. We then cover essential methods for modifying arrays like .push(), .pop(), and the powerful .splice(). You'll learn the best ways to loop over arrays, including the classic for loop and the modern for...of loop.

But we don't stop there. This lecture goes deep into the most critical concepts for writing clean, efficient code:
The "powerhouse" methods of modern JavaScript: .map(), .filter(), and .reduce().
The crucial difference between mutating and non-mutating methods.
And finally, we'll prove a fundamental truth: why a JavaScript array is NOT a "real" array like in other languages (e.g., C++). Understanding that it's actually an object is the key to avoiding common bugs.
🎓 WHAT YOU WILL LEARN IN THIS LECTURE:
Part 1: The Fundamentals
What is an Array? Creating arrays and the .length property.
Accessing and Modifying Elements (Zero-Based Indexing).
Basic Array Modification: .push(), .pop(), .shift(), and .unshift().
Part 2: Iteration & Looping
How to loop with a classic for loop.
The modern and preferred way: the for...of loop.
Part 3: The Powerhouse Methods (Modern JavaScript)
.map(): How to transform every element into a new array.
.filter(): How to create a new array with only the elements that pass a test.
.reduce(): How to "roll up" an entire array into a single value (like a sum).
Part 4: Advanced Concepts & Utilities
Sorting Arrays Correctly: The .sort() method and its critical compare function (a, b) = a - b.
Flattening Nested Arrays with .flat().
The Right and Wrong Way to Delete Elements (splice vs. the delete operator).
Copying vs. Referencing: Why let copy = original is a trap and how to use the Spread Operator (...).
Arrow Functions () {} explained in the context of array methods.
Converting Arrays to Strings with .join().
Finding Items: .find(), .findIndex(), and .includes().
Part 5: The Deep Dive
The Truth About Arrays: Proving that a JavaScript Array is actually an object.
Understanding "Sparse Arrays" and why they can be problematic.
👨‍💻 WHO IS THIS VIDEO FOR?
JavaScript beginners who want a complete guide to arrays.
Developers who want to master modern array methods like map, filter, and reduce.
Students preparing for technical interviews where array manipulation is a core skill.
Anyone who wants to write cleaner, more functional, and more efficient JavaScript code.


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Course start date: 1 september
Timing: 6pm (Mon-fri)
Hackathon will be organised after course completion
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Time Stamp:
0:00 Introduction
1:32 What is an Array?
3:20 Printing Array Elements
3:53 Getting Array Length
4:20 Heterogeneous Data Types in JavaScript Arrays
5:37 Accessing Elements by Index
6:17 Array is Mutable
7:50 Adding Elements to the End
8:53 Removing Elements from the End
9:43 Adding Elements to the Beginning
11:04 Removing Elements from the Beginning
11:25 Why Avoid unshift() and shift()
14:07 Iterating with for Loop
16:50 Iterating with for...of Loop
17:41 Copying Arrays: Copy by Reference
22:09 Using const with Array
27:12 Slicing Array
28:18 Splicing Array
31:35 Merging Array with Spread Operator
37:10 Converting Array to String
39:11 Searching in Array
40:43 Sorting Array of String
43:36 Reversing Array Order
44:40 Why Default Sort Fails for Numbers
46:49 Reason Behind JavaScript’s Default Sort
48:58 Custom Sorting: Ascending Order
53:05 Custom Sorting: Descending Order
54:09 Flattening Nested Array
59:39 Why JavaScript Arrays Are Not "True" Array
1:03:10 Array Behaving Like Objects
1:09:01 Wrapping Up



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