Array creation

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What is an Array?

An array is a data structure in JavaScript that allows you to store multiple values in a single variable. Each value in an array is called an element, and each element is assigned a unique index starting from 0.

Arrays can hold values of different data types, including numbers, strings, booleans, objects, and even other arrays. This makes arrays a versatile tool for storing and manipulating collections of data.

Creating an Array

In JavaScript, you can create an array using the array literal syntax, which consists of square brackets `[]`. Inside the brackets, you can list the elements of the array, separated by commas. Here's an example of creating an array with three elements:

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

In the example above, we create an array called `fruits` containing three strings: "apple", "banana", and "orange".

You can also create an empty array by omitting the elements inside the brackets:

let emptyArray = [];

Accessing Array Elements

Once you have created an array, you can access its elements using their index. The index is the position of an element within the array, starting from 0 for the first element.

To access an element, you can use square brackets `[]` with the index inside them. Here's an example:

let fruits = ["apple", "banana", "orange"];
 
console.log(fruits[0]); // Output: "apple"
console.log(fruits[1]); // Output: "banana"
console.log(fruits[2]); // Output: "orange"

In the example above, we access the first, second, and third elements of the `fruits` array using their respective indices.

Modifying Array Elements

You can modify the elements of an array by assigning a new value to a specific index. Here's an example:

let fruits = ["apple", "banana", "orange"];
 
fruits[1] = "grape";
 
console.log(fruits); // Output: ["apple", "grape", "orange"]

In the example above, we modify the second element of the `fruits` array by assigning the value "grape" to index 1.

Adding and Removing Array Elements

JavaScript provides several methods to add and remove elements from an array. Here are some commonly used methods:

  • `push()`: Adds one or more elements to the end of an array.

  • `pop()`: Removes the last element from an array.

  • `unshift()`: Adds one or more elements to the beginning of an array.

  • `shift()`: Removes the first element from an array.

Here's an example that demonstrates these methods:

let numbers = [1, 2, 3];
 
numbers.push(4);
console.log(numbers); // Output: [1, 2, 3, 4]
 
numbers.pop();
console.log(numbers); // Output: [1, 2, 3]
 
numbers.unshift(0);
console.log(numbers); // Output: [0, 1, 2, 3]
 
numbers.shift();
console.log(numbers); // Output: [1, 2, 3]

In the example above, we add an element to the end of the `numbers` array using `push()`, remove the last element using `pop()`, add an element to the beginning using `unshift()`, and remove the first element using `shift()`.

Key Takeaways

  • Arrays in JavaScript allow you to store and access multiple values using a single variable.

  • Use square brackets `[]` to create an array and separate the elements with commas.

  • Arrays are zero-indexed, meaning the first element has an index of 0.

  • You can modify array elements by assigning new values to specific indices.

  • JavaScript provides methods like `push()`, `pop()`, `unshift()`, and `shift()` to add and remove elements from an array.

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