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JS TutorialLesson #67

The new Array() Constructor

The new Array() constructor creates an Array object.

The new Array() constructor creates an Array object.

Syntax

Example Code

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new Array()

new Array(number)

new Array(element1, element2, ..., elementN)

Array()

Array(number)

Array(element1, element2, ..., elementN)

Examples

Example Code

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new Array()

new Array(3)

new Array("3")

new Array("Saab", "Volvo", "BMW")

Syntax	Description
new Array()	Creates an empty array.
new Array(x)	Creates an array with x empty spots.
new Array(elem1)	Creates an array with one element.
new Array(elem1,...,elemN)	Creates an array with multiple elements.

The Difference? new Array() vs Array()

The short answer is: there is no functional difference between new Array() and Array().

Both commands do the exact same thing and create an array.

Note > The Array creator function is smart. > It is programmed to check if you forgot the new keyword. > If you leave it out, it adds it behind the scene.

JavaScript new Array()

JavaScript has a built-in array constructor new Array().

But you can most often use [] instead.

These two different statements both create a new empty array named points:

Example

Example Code

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const points = new Array();

const points = [];

These two different statements both create a new array containing 6 numbers:

Example

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const points = new Array(40, 100, 1, 5, 25, 10);

const points = [40, 100, 1, 5, 25, 10];

The new keyword can produce some unexpected results:

Example

Example Code

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// Create an array with three elements:

const points = new Array(40, 100, 1);

Example

Example Code

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// Create an array with two elements:

const points = new Array(40, 100);

Example

Example Code

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// Create an array with one element ???

const points = new Array(40);

A Common Error

Example Code

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const points = [40];

Example

Example Code

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// Create an array with one element:

const points = [40];

Example

Example Code

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// Create an array with 40 undefined elements:

const points = new Array(40);

Important Warning > Use an array literal [ ] instead of the new Array() when possible. > new Array(number) is a special dangerous case. > new Array(3) creates an array with 3 empty elements; not an array containing the number 3. > Using [ ] is faster to type, easier to read, and avoids the "single number trap": > For example, [3] actually creates [3], not [null,null,null].

Array Literal (Preferred)

The recommended way to create an array is with an array literal:

Example

Example Code

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const cars = ["Saab", "Volvo", "BMW"];

Learn More: > Array Tutorial > Array Methods > Array Search Methods > Array Sort Methods > Array Iteration Methods > Full JavaScript Array Reference

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