javascript-array-group/ about dmitripavlutin.com-comments HOT 16 OPEN

Yet another great post DP with new info and clear exp !!

Thanks @kishoreandra!

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The benefit of Map is that it accepts any data type as a key, but the plain object is limited to strings only.

As I know, a plain object is limited to strings and symbols, am I right?

Strictly, you're right that strings and symbols are keys in plain objects. But I almost always use strings as keys.

But I updated the post per your suggestion. Thanks @ipovos.

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This article should be updated because now they rename it to Object.groupBy: https://github.com/tc39/proposal-array-grouping

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@aralroca Thanks. Post updated.

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Yet another great post DP with new info and clear exp !!

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The benefit of Map is that it accepts any data type as a key, but the plain object is limited to strings only.

As I know, a plain object is limited to strings and symbols, am I right?

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Second time google directed me to your useful information, thanks for sharing and for this blog.
Alex

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appreciate the post,
I have used node 16 and node 18 to used groupBy method on an arry and both time it throw an error saying products.groupBy is not a function
any idea? thanks

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Hey @yusuf963, please have a look at this issue (on group for group by) and it should be used carefully until it ships and official by ES committee... https://github.com/tc39/proposal-array-grouping#why-group-and-not-groupby

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Couldn't your groupToMap example just have used group() seeing as it's using strings as keys? I would find it more instructive if it had returned something that actually needed to be a Map

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Couldn't your groupToMap example just have used group() seeing as it's using strings as keys? I would find it more instructive if it had returned something that actually needed to be a Map

@o-t-w Feel free to create a Pull Request for this post with a more meaningful example. 🎸

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Is there a way to use this and show the output in an

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Quick question, how do I map out the grouped data?

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Quick question, how do I map out the grouped data?

@o-david Can you give more details what you want to achieve?

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Made a test example with Object.groupBy and two Array.reduce functions, one with a body like in your article, and another reduce slightly optimized:
https://jsperf.app/raxofi
It appears that in Chrome 118 Object.groupBy is performing slightly slower than optimized Array.reduce, while unoptimezed Array.reduce is 1/3 slower.

Optimization is done on resulting grouping object updating, originally you have to access group[category] THREE times:

  group[category] = group[category] ?? [];
  group[category].push(product);

Instead you can write:

group[category]?.push(product) ?? ( group[category] = [ product ] );

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Now is there any way to make it work with TypeScript?
I tried adding the following option to tsconfig.json but it still reports the error Property 'groupBy' does not exist on type 'ObjectConstructor'.ts(2339).

    "target": "esnext",
    "lib": ["ESNext"],

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