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Getting the frequency of an element in an array in JavaScript

Perelyn-sama on December 06, 2020

First of all, what is frequency? According to Wikipedia, it's" the rate at which something occurs over a particular period of time or in a given sa...
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Kai •

There's no need for nums.map(e => Number(e)). Here, you are transforming numbers to... well, numbers. You can skip this step. If you really want to convert them to strings you should use either String(e) or e.toString().

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Perelyn-sama •

I'm sorry It's a typo, I originally wanted to write String(e). Thanks for pointing out to me

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Zen •

You can change Number(e) with +e

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keogami •

Thats too hacky and non intuitive i.e. not readable. As a simple rule you must avoid being clever because readable code is always better than clever code 😊

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Perelyn-sama •

True, simple code is good code.

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Perelyn-sama •

Thanks for the pointer.

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Rishit Khandelwal •

We could just use Array.reduce

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Perelyn-sama •

Yeah, there's more that one way to skin a cat

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Rishit Khandelwal • 
const count=(i,w)=>i.reduce((a,v)=>v==w?a+1:a,0)
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Perelyn-sama •

Thanks!

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Nguyen Tran Chau Giang • 
const letters = ["a", "b", "c", "a", "b", "c", "a", "b"];
const countLetters = letters.reduce((m,n)=>({...m, [n]:-~m[n]}),{})

// For nums, it is the same
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Perelyn-sama •

Wow thanks, that's awesome and shorter

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Nguyen Tran Chau Giang •

no problems, keep learning !

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Adam Nathaniel Davis •

Why would you need to do this any differently for numbers vs strings?? The first example (the one that you show as being "for string elements") works just fine if you pass in the array of numbers.

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Perelyn-sama •

Wow, I never realized that. Thanks for the pointer, I'll the remove the 'For numbers' part.

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Angela Inniss •

Thanks for this. This is good for beginners like me as it says in the tags. Some of the other suggestions are cool too but a bit more confusing :)

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keogami •

Ngl the "for numbers" part is stupid

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Perelyn-sama •

That I agree with, thanks for your feedback