A JavaScript array is a single variable that stores different elements. It is often used when we want to store a list of elements and access them by a single variable1. Arrays are a special type of object. The typeof operator in JavaScript returns “object” for arrays.
If you have a list of elements (a list of fruits, for example), storing the fruits in a single variable could look like the following code.
let x = "me";
let u = "sunflower";
let v = "smooth criminal";However, what if you want to loop through the songs and find a specific one? And what if you had not three songs but 300?
The solution is an array!
The array can hold many values under a single name, and you can access the values by referring to the index number.
How to Create an Array in JavaScript
To create an array in JavaScript, use an array literal or by creating the instance of an Array directly (using the new keyword) or by utilizing the Array constructor.
JavaScript array literal
The syntax of creating an array using array literal is given below.
var array = [1, 2, 3];
let array = [1, 2, 3];
const array = [1, 2, 3];JavaScript array directly (new keyword)
To create an array directly, use the new keyword in JavaScript. The syntax for creating an array directly is given below.
Syntax
let arrayname = new Array();Example
let arr = new Array();
arr.push(4, 9, 16)
console.log(arr);Output
In the above example, we have used the array push() function.
JavaScript array constructor (new keyword)
In JavaScript, you can declare an array using the new keyword to instantiate the array in memory.
For example, here’s how to declare a new Array() constructor: let x = new Array(); This creates an empty array.
let arr = new Array(4, 9, 16);
console.log(arr);Output
How to access array elements in JavaScript
To access the elements in the JavaScript array, use the array index. You can access an element using square brackets; the array index starts from 0.
let arr = new Array(4, 9, 16);
console.log(arr[0]);
console.log(arr[1]);
console.log(arr[2]);Output
You can also use the forEach function to print the value individually.
How to change Array element in JavaScript
To change an array element in JavaScript, use the element index.
let arr = new Array(4, 9, 16);
console.log('Before modify: ', arr);
arr[0] = 25;
arr[1] = 36;
arr[2] = 49
console.log('After Modify: ', arr);Output
Arrays are Objects
Arrays are a special type of object. The typeof operator in JavaScript returns an “object” for arrays. But JavaScript arrays are best described as arrays.
JavaScript variables can be objects. Arrays are particular kinds of objects. Because of this, you can have variables of different types in the same Array.
You can have objects in an Array. You can have functions in an Array. You can have arrays in an Array.
Array Properties and Methods
JavaScript arrays have properties and methods. It is their real strength.
let arr = new Array(4, 9, 16);
console.log('Array length is: ', arr.length);Output
Array Properties
Here is the list of the properties of the Array object, along with their description.
| Sr.No. | Property & Description |
|---|---|
| 1 | constructor
Returns the reference to the array function that created the object. |
| 2 | index
The property represents a zero-based index of the match in the string |
| 3 | input
This property is only present in the arrays created by regular expression matches. |
| 4 | length
Reflects the number of elements in the array. |
| 5 | prototype
The prototype property allows you to add properties and methods to the object. |
Associative Array in Javascript
JavaScript does not support associative arrays because JavaScript does not support arrays with named indexes. Instead, in JavaScript, arrays always use numbered indexes.
Many programming languages support arrays with named indexes. Arrays with named indexes are called associative arrays (or hashes).
When to Use Arrays. When to use Objects.
- JavaScript does not support associative arrays.
- You should use the objects when you want the element names to be strings (text).
- You should use the arrays when you want item names to be numbers.
JavaScript Array Methods
That’s it for this tutorial.
