Throwing StopIteration in array extras to stop the iteration
brendan at mozilla.com
Mon Mar 4 12:28:44 PST 2013
One idea we've discussed: allow the sentinel that is OOB with respect to
the domain (element type) be an optional second parameter:
const K = Symbol("not found");
console.log( [1, 2, 3].find(x => isNaN(x), K) ); // K, logs as "not
console.log( [1, 2, , 3].find(x => isNaN(x)) ); // undefined
P.S. Don't use isNaN! I know, it served your example's purpose.
Domenic Denicola wrote:
> From: es-discuss-bounces at mozilla.org [es-discuss-bounces at mozilla.org] on behalf of Rick Waldron [waldron.rick at gmail.com]
>> Thanks, I've submitted an agenda item that includes _both_ find and findIndex.
> One issue with `find` is what distinguishes
> find([1, 2, 3], x => isNaN(x)); // presumably `undefined`
> find([1, 2, undefined, 3], x => isNaN(x)); // also presumably `undefined`
> i.e. how do you distinguish "found nothing" from "found `undefined`."
> In C# they have `IEnumerable<T>.First` and `IEnumerable<T>.FirstOrDefault`; the former throws an error if nothing matching the predicate is found, whereas the latter returns `default(T)` (which is `null` for reference types, or `0` for numbers, etc.).
> Food for thought.
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