What’s the difference between “Array()” and “[]” while declaring a JavaScript array?

When it comes to declaring an array in JavaScript, you might have come across two different syntaxes: Array() and []. While both can be used to create arrays, there are some key differences between them. In this article, we will explore these differences and understand when to use each syntax.

The Array() Constructor

The Array() constructor is a built-in JavaScript function that can be used to create an array object. It can be called with or without the new keyword:

// Using the Array() constructor with the new keyword
    const myArray = new Array();

    // Using the Array() constructor without the new keyword
    const myArray = Array();

When called without any arguments, the Array() constructor creates an empty array. However, you can also pass one or more arguments to initialize the array with specific values:

// Initializing an array with specific values using the Array() constructor
    const myArray = new Array('apple', 'banana', 'cherry');

It’s important to note that if you pass a single numeric argument to the Array() constructor, it will be treated as the length of the array rather than the value:

// Creating an array with a specific length using the Array() constructor
    const myArray = new Array(5); // Creates an array with a length of 5

The [] Literal Syntax

The [] syntax, also known as array literal syntax, is a shorthand way to create an array in JavaScript:

// Creating an array using the array literal syntax
    const myArray = [];

Similar to the Array() constructor, you can also initialize the array with specific values:

// Initializing an array with specific values using the array literal syntax
    const myArray = ['apple', 'banana', 'cherry'];

Key Differences

While both Array() and [] can be used to create arrays, there are a few differences worth noting:

• The Array() constructor can be called with or without the new keyword, while the [] syntax is always used without new.
• If you pass a single numeric argument to the Array() constructor, it will be treated as the length of the array. In contrast, using [] with a single numeric argument will create an array with that value as the first element.
• The [] syntax is generally preferred and more commonly used in modern JavaScript development due to its simplicity and readability.

Conclusion

Both Array() and [] can be used to create arrays in JavaScript. The choice between them depends on your specific use case and personal preference. While the Array() constructor offers more flexibility, the [] syntax is simpler and more commonly used in modern JavaScript development.