Array access

Learn to access array elements by index.

Array access

To reach an element of an array you use an index: arr[0], arr[1] and so on. The index goes inside square brackets. Indexing is zero-based: the first element is arr[0], the second arr[1].

For example const fruits = ["apple", "pear", "banana"]; fruits[0] gives "apple", fruits[2] gives "banana". An index past the array length returns undefined; no error is thrown. For example fruits[5] is undefined. So checking array bounds with arr.length is a good habit.

Zero-based indexing

In JavaScript indices start at zero. This means the last element's index is arr.length - 1. In a three-element array the last element is arr[2], because the length is 3 and 3 - 1 = 2.

Zero-based indexing takes getting used to but is standard in programming. Negative indices are not directly supported; arr[-1] returns undefined. To reach the last element write arr[arr.length - 1]. As a shorter way arr.at(-1) can be used; this method supports negative indices.

Exercise Print the second element

The fruits variable is set to ["apple", "pear", "banana"]. Declare a variable second and assign the result of fruits[1] to it. Then print second with console.log. The output on a single line must be pear.

Show example solution

const fruits = ["apple", "pear", "banana"];
const second = fruits[1];
console.log(second);

Test yourself

Access the first element

const fruits = ["apple", "pear", "banana"];
const first = fruits____;

Show answer

const fruits = ["apple", "pear", "banana"];
const first = fruits[0];

What is const a = [10, 20, 30]; a[2]?
```
const a = [10, 20, 30];
a[2]
```
- 20
- 30
- 10
- 3
Show answer

30 — a[2] gives the third element, 30.
Match each index to its position

[0]

First element
[1]

Second element
[length - 1]

Last element
[length]

undefined

Next lesson: push and pop

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