Book Image

Learning JavaScript Data Structures and Algorithms

By : Loiane Avancini
Book Image

Learning JavaScript Data Structures and Algorithms

By: Loiane Avancini

Overview of this book

Table of Contents (18 chapters)

Creating and initializing arrays


Declaring, creating, and initializing an array in JavaScript is as simple, as follows:

var daysOfWeek = new Array(); //{1}
var daysOfWeek = new Array(7); //{2}
var daysOfWeek = new Array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'); //{3}

We can simply declare and instantiate a new array by using the keyword new (line {1}). Also, using the keyword new, we can create a new array specifying the length of the array (line {2}). And a third option would be passing the array elements directly to its constructor (line {3}).

However, using the new keyword is not a best practice. If you want to create an array in JavaScript, simply use brackets ([]) like in the following example:

var daysOfWeek = [];

We can also initialize the array with some elements, as follows:

var daysOfWeek = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

If we would like to know how many elements are in the array, we can use the length...