Array.of()
The Array.of()
method creates a new Array
instance from a variable number of arguments, regardless of number or type of the
arguments.
Syntax
Array.of(element0)
Array.of(element0, element1)
Array.of(element0, element1, /* … ,*/ elementN)
Parameters
elementN
- : Elements used to create the array.
Return value
A new Array
instance.
Description
The difference between Array.of()
and the Array()
constructor is in the handling of single arguments: Array.of(7)
creates an array with a single element, 7
, whereas Array(7)
creates an empty array with a length
property of 7
. (That implies an array of 7 empty slots, not slots with actual undefined
values.)
Array.of(7); // [7]
Array(7); // array of 7 empty slots
Array.of(1, 2, 3); // [1, 2, 3]
Array(1, 2, 3); // [1, 2, 3]
The Array.of()
method is a generic factory method. For example, if a subclass of Array
inherits the of()
method, the inherited of()
method will return new instances of the subclass instead of Array
instances. In fact, the this
value can be any constructor function that accepts a single argument representing the length of the new array, and the constructor will be called with the number of arguments passed to of()
. The final length
will be set again when all elements are assigned. If the this
value is not a constructor function, the plain Array
constructor is used instead.