Array subclassing, .map and iterables (Re: Jan 30 TC39 Meeting Notes)

[Allen Wirfs-Brock]

On Feb 10, 2013, at 1:04 PM, Tab Atkins Jr. wrote:
> 
> From what I've seen in the examples in this topic so far, it looks
> like Array#from takes a second optional argument, which is a function
> that you map the iterable elements through first, before giving them
> to the constructor.  So, you would write:
> 
> NodeList.from( ["div", "span", "p"],
> (nodeName)=>document.createElement(nodeName) );
> 

Exactly.

Of course, in defining 
       class NodeList extends Arrar {...}
 you could decide to over-ride the inherited definition of .from with a version that implicitly did the above coercion on string valued elements.  It up to the designer of the class interface.

Allen

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