Why is using "new" to create a Javascript array considered bad? [duplicate]

Question

W3 Schools says

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

 var points = new Array(40, 100, 1, 5, 25, 10)  // Bad 
 var points =[40, 100, 1, 5, 25, 10];          // Good

but doesn't give an explanation why the first is bad.

From what I understand, the only difference is that the first calls the constructor. Can someone clue me into why the first is bad?

Answer 1

The true reason is that this constructor is inconsistent.

var points = new Array(40)

creates an array of size 40 and no content while

var points = new Array(40, 50)

creates an array of size 2 with 2 elements.

It's just simpler and more readable to use

var points = [40];

or

var points = [40, 50];

There's also no reason to use this constructor when you want to build a array, just use a literal array, exactly like you're using literal numbers.

Only use the Array constructor when you want to build an empty array with a given size (which should be very rare).

ES 2015 edit:

Due to this inconsistency, ES2015 brought us a new static function, Array.of. Array.of(40) makes the [40] array.