Merge map values

Mohan.Radhakrishnan at Mohan.Radhakrishnan at
Tue Apr 28 12:42:29 UTC 2015

I agree this is not about the ES6 spec. But the answers helped because I was trying to understand ES6’s arrow function that is similar to lambdas.


From: Andrea Giammarchi [mailto:andrea.giammarchi at]
Sent: Tuesday, April 28, 2015 6:02 PM
To: Kevin Smith
Cc: Axel Rauschmayer; Radhakrishnan, Mohan (Cognizant); es-discuss list
Subject: Re: Merge map values

Not sure why everyone went for the `Map` version when in JS every object is basically the equivalent of a `Map` already :-)

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 <zenparsing at<mailto:zenparsing at>> wrote:

Another option:

    var map = new Map;
      .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.

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