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Lesson Notes

Accessing Array Elements by Index in JavaScript

Arrays in JavaScript are zero-indexed, meaning the first element is at position 0.

Example Array

const names = ["John", "Mary", "Susie", "Jay", "Edward", "Mike"];
console.log(`All names: ${names}`);
// Outputs: All names: John,Mary,Susie,Jay,Edward,Mike

Getting the Length

console.log(`Length of array: ${names.length}`);
// Outputs: Length of array: 6

Accessing by Index

Index 0: First element
Index 1: Second element
…
Index 5: Sixth element (last, since length is 6)

console.log(names[0]); // "John"
console.log(names[4]); // "Edward"
console.log(names[5]); // "Mike"

Key Points

Indexes start at 0, so the last element is at length - 1.
Use array[index] to retrieve or modify elements.

Why It Matters

Looping over arrays often uses indexes:

for (let i = 0; i < names.length; i++) {
  console.log(`Name at index ${i}: ${names[i]}`);
}

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Exploring Array Properties

Array Iteration with JavaScript For Loops

Array Indexing, Access Elements

In this lesson, students will learn how to access and manipulate array elements in JavaScript using their indices, understanding the concept of zero-based indexing. By mastering these skills, learners will be equipped to efficiently work with arrays and enhance their programming capabilities.

2m 32s