Indexes and length

#description

In JavaScript, indexes and length are two important concepts that are used extensively while working with arrays and strings.

Indexes: An index is simply a numeric value that represents the position of an element in an array or a character in a string. The index of the first element in an array or first character in a string is always 0. The second element or character has an index of 1, and so on.

For example, consider the following array:

                    
let fruits = ['apple', 'banana', 'orange'];

The index of the first element 'apple' is 0, the index of the second element 'banana' is 1, and the index of the third element 'orange' is 2.

To access a specific element in an array using its index, you can use the bracket notation with the index value as the parameter.

For example,

                    
let firstFruit = fruits[0]; //Access the first element 'apple'
let secondFruit = fruits[1]; //Access the second element 'banana'

Length: The length property is used to get the number of elements in an array or the number of characters in a string.

For example, the length of the 'fruits' array in the above example is 3. To get the length of an array or a string, you can use the .length property.

For example,

                    
let fruitLength = fruits.length; //Get the length of the fruits array (3)

Understanding indexes and length is critical while working with arrays and strings in JavaScript as they enable efficient manipulation and access of data.

March 25, 2023

If you don't quite understand a paragraph in the lecture, just click on it and you can ask questions about it.

If you don't understand the whole question, click on the buttons below to get a new version of the explanation, practical examples, or to critique the question itself.

Developer learning path

Indexes and length in JavaScript

Indexes and length