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From: Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups: comp.lang.javascript
Subject: Re: is there a function enumerating all element in an object?
Date: Thu, 29 Oct 2015 20:49:25 +0000
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"Evertjan." <exxjxw.hannivoort@inter.nl.net> writes:

> Joao Rodrigues <groups_jr-1@yahoo.com.br> wrote on 29 Oct 2015 in 
> comp.lang.javascript:
>
>>> Object.keys(obj).map(key => callback(key, obj[key]));
>> Or:
>> 
>> Array.from(Object.keys(obj), key => callback(key, obj[key]));
>
> Could you please explain to us simple minded how this realy works?

In ES6, the form

  x => expression

is similar to

  function (x) { return expression; }

There are a few differences ("this" is lexical in an arrow function and
there is no "arguments" object) but neither of those matter here I don't
think.

[You may have multiple parameters:

  (a, b) => a + b

and you may have an explicit block rather than a single expression:

  x => { console.log(`x = ${x}`); return x; }

which sneaks in another ES6 feature: template strings.]

-- 
Ben.