No engine has implemented subclassing of `Array`, yet:
http://kangax.github.io/compat-table/es6/#Array_is_subclassable
<http://kangax.github.io/compat-table/es6/#Array_is_subclassable>
And, as Sebastian mentioned, you can’t transpile it, because it depends on the
cooperation of `Array`: it becomes the base constructor and allocates an exotic
array instance (with special handling for `length` etc.) whose prototype is
`new.target`.
Axel
> On 11 Apr 2015, at 03:57, Garrett Smith <dhtmlkitc...@gmail.com> wrote:
>
> On 4/10/15, Axel Rauschmayer <a...@rauschma.de> wrote:
>> The reason why you need to call the super-constructor from a derived class
>> constructor is due to where ES6 allocates instances - they are allocated
>> by/in the base class (this is necessary so that constructors can be
>> subclassed that have exotic instances, e.g. `Array`):
>>
> Can you please explain how extending Array works. Also what is the
> optional identifier optional for in ClassExpression:
>
> var myArray = (new class B extends Array {
> constructor() {
> super(1,2,3,4,5);
> }
> });
> alert(myArray.length); // it's 0 in Babel.
>
> --
> Garrett
> @xkit
> ChordCycles.com
> garretts.github.io
> personx.tumblr.com
--
Dr. Axel Rauschmayer
a...@rauschma.de
rauschma.de
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