Creating and initializing arrays

Declaring, creating, and initializing an array in JavaScript is really simple, as the following shows:

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

We can simply declare and instantiate a new array 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}). A third option would be passing the array elements directly to its constructor (line {3}).

However, using the new keyword is not considered best practice. If we want to create an array in JavaScript, we can assign empty brackets ([]), as in the following example:

let daysOfWeek = []; 

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

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

If we want to know how many elements are in the array ...