On Thu, May 31, 2012 at 7:01 PM, Mark S. Miller <[email protected]> wrote:
snip
> // Imaginary DOM library
>> DOM = {};
>>
>> // This function accepts a function as it's second argument,
>> // what happens when its a bound function? I'd like write the
>> // API in a way that is friendly to both types of function
>>
>> DOM.each = function( elems, callbackFn ) {
>> var bound;
>>
>> // I made this up, but it makes sense because fat arrows don't
>> // have a prototype, so Function.prototype.isBound() is out
>>
>
> fat arrow functions don't have a ".prototype" but they do have a
> [[Prototype]] of Function.prototype, and so would still inherit
> Function.prototype.isBound() as an instance method. No matter, I don't
> really care what the predicate is named, which way the truth value goes, or
> how it is invoked. So far, this example is fine.
>
Wouldn't this mean that fat arrow functions inherit call, apply and bind as
well? (I may have misunderstood this aspect)
>
>> //
>> if ( !Function.isBound(callbackFn) ) {
>> // When not explicitly bound,
>> // DOM.each sets |this| to the object being iterated
>> bound = callbackFn.bind( elems );
>> }
>>
>
> I don't understand. Here, you're conditionally assigning the newly bound
> function bound to the "bound" variable. But then you're not using the
> "bound" variable anywhere. Binding itself has no side effect, so this code
> seems like a noop. Typo?
>
Yes, sorry, that is a typo - I put this example together quickly, I
should've reviewed it a little more thoroughly. Sorry for the confusion.
Rick
>
>
>
>> [].forEach.call( elems, callbackFn );
>> }
>>
>> let nodes = document.querySelectorAll(".theclass");
>>
>> DOM.each( nodes, function( index ) {
>> // the node is at: this[ index ]
>> });
>>
>>
>> function ListOfNodes( selector ) {
>> let nodes = document.querySelectorAll( selector );
>>
>> // I don't want to return a NodeList, I'm
>> // making my own API - WOO!
>>
>> DOM.each( nodes, index => {
>>
>> // |this| is the constructed instance
>> this[ index ] = nodes[ index ];
>>
>> });
>>
>> this.length = nodes.length;
>> }
>>
>> // I might make my own API for
>> // manipulating my ListOfNodes
>> // ListOfNodes.prototype.foo...
>>
>>
>> var list = new ListOfNodes(".class");
>>
>> list;
>>
>> > [ div.class, div.class (use imagination) ]
>>
>>
>>
>> Hopefully this helps!
>>
>> Rick
>>
>
>
>
> --
> Cheers,
> --MarkM
>
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