Page 87 - JavaScript

length with all undefined values will be created instead:

var arr4 = new Array(4);

results in:

[undefined, undefined, undefined, undefined]

That does not apply if the single argument is non-numeric:

var arr5 = new Array("foo");

results in:

["foo"]

6

Similar to an array literal, Array.of can be used to create a new Array instance given a number of
arguments:

Array.of(21, "Hello", "World");

results in:

[21, "Hello", "World"]

In contrast to the Array constructor, creating an array with a single number such as Array.of(23)
will create a new array [23], rather than an Array with length 23.

The other way to create and initialize an array would be Array.from

var newArray = Array.from({ length: 5 }, (_, index) => Math.pow(index, 4));

will result:

[0, 1, 16, 81, 256]

Array spread / rest

Spread operator

6

With ES6, you can use spreads to separate individual elements into a comma-separated syntax:

let arr = [1, 2, 3, ...[4, 5, 6]]; // [1, 2, 3, 4, 5, 6]

https://riptutorial.com/ 44