Array in Javascript

Creating an array using array literal

In JavaScript, we can create an array using an array literal, which is a list of values enclosed in square brackets []. The values enclosed within the brackets are elements of an array which can hold any data type.

Syntax

let arrayName = [element1, element2, ...];

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Here,

• let: This keyword is used to declare a variable.
   
• arrayName: It is the name of our array.
   
• element1, element1: These are the elements of our array.

Example

• JavaScript

JavaScript

// Initializing first array
let names = ["Smith", "Bob", "Mark", "Luke"];
console.log(names)

//Initializing second array
let marks = [70, 81, 93, 78];
console.log(marks)

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Output

Explanation

In the above example, we initialized and displayed two array names and marks using array literals. The first array holds values of string types, while the other has values of type numbers.

Creating instance of Array directly (using new keyword)

In JavaScript, we can create an instance of an array directly using the new keyword followed by the Array constructor. The Array constructor is an in-built function using which we can create new arrays in JavaScript.

Syntax

let arrayInstance = new Array();

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Here, 

• arrayInstace: It is the name of our array variable.
   
• new Array(): The new keyword creates a new instance of the Array() constructor. If no values are defined, then it will create an empty array.

Example

• JavaScript

JavaScript

// Declaring the array
let student = new Array();

// Before initializing
console.log("Before initializing: ");
console.log(student);

student[0] = "Smith";  
student[1] = "John";  
student[2] = "David";

// After initializing
console.log("After initializing: ");
console.log(student);

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Output

Explanation

In the above example, we created an instance of an array using the new keyword and the Array constructor, which will create an empty array for us. After that, we explicitly passed the array elements and printed them using the console.log() method.

Using an Array constructor (using new keyword)

In this method, we don't need to pass the array elements explicitly. Instead, we can pass them as arguments in the Array constructor itself.

Syntax

let arrayName = new Array(element1, element2, ...);

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Here, 

• arrayName: It is the name of our array variable.
   
• new Array(): The new keyword is used to create a new instance of the Array constructor.
   
• element1, element2: These are the elements of our array which are passed during array initialization.

Example

• JavaScript

JavaScript

// Creating an array of number
let numbers = new Array(1, 2, 3, 4, 5);
console.log(numbers);
console.log();

// Creating an array of strings
let names = new Array("Smith", 'Bob', 'David');
console.log(names);

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Output

Explanation

In the above example, we created an array using the Array constructor and a new keyword by passing the arguments directly while declaring the array.

JavaScript Array Methods

Now, let us look at some JavaScript array method and their description.

Check out this problem - First And Last Occurrences Of X

Frequently Asked Questions

What is an array in JavaScript?

In JavaScript, an array is a fundamental data structure. An array is a special type of object that can store multiple values under a single variable. Unlike other languages, arrays in JavaScript can have values of different data types, such as numbers, strings, and objects.

How many types of arrays are there in JS?

In Javascript, arrays are divided into two types, one-dimensional arrays and multi-dimensional arrays. The one-dimensional or linear array consists of only one row or column. Meanwhile, a multi-dimensional array consists of one or more nested arrays.

What are two forms of array?

In Javascript, there are two forms of arrays literal arrays and constructed arrays. The literal arrays are created using the array literal enclosed within square brackets []. The constructed arrays are created using the new keyword and the Array constructor function.

Conclusion

In this article, we discussed the topic of Arrays in JS. We started by introducing arrays in general. Later on, we discussed declarations, functionalities, methods, loops, 2D arrays and what not to do in arrays.

We hope this blog has helped you enhance your knowledge of Arrays in JS. If you want to learn more, then check out our articles.

• Array Methods in JavaScript
• Basics of JavaScript
• Best Practice in JS
• Difference Between Array List and Linked List
   

And many more on our platform Coding Ninjas Studio.

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