With Maps, there are less pitfalls. For example: what if you want to use your version to count words and one of the words is `__proto__`? Most pitfalls can be fixed via `Object.create(null)`, but Maps are more straightforward for data (vs. code).
But your version can be easily adapted to Maps, I like the way you use `reduce()`. The `|` should be a `||`. > On 28 Apr 2015, at 14:31 , Andrea Giammarchi <[email protected]> > wrote: > > Not sure why everyone went for the `Map` version when in JS every object is > basically the equivalent of a `Map` already :-) > > ```js > let m = Array.from("mainn").reduce((m,k) => ((m[k] = 1 + (m[k] | 0)), m), {}); > ``` > > looks a win to me, if you need to check or drop chars from the string I would > probably do it once before passing that to `Array.from` > > Agreed with Kevin this is rather a StackOverflow like question :-) > > Best Regards > > > On Tue, Apr 28, 2015 at 1:19 PM, Kevin Smith <[email protected] > <mailto:[email protected]>> wrote: > Another option: > > var map = new Map; > Array.from("mainn") > .map(c => c.toLowerCase()) > .forEach(c => map.set(c, (map.get(c) | 0) + 1)); > > This kind of question is probably better left for StackOverflow, however. > > > _______________________________________________ > es-discuss mailing list > [email protected] <mailto:[email protected]> > https://mail.mozilla.org/listinfo/es-discuss > <https://mail.mozilla.org/listinfo/es-discuss> > > -- Dr. Axel Rauschmayer [email protected] rauschma.de
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