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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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bugb
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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bugb

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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keogami

Ngl the "for numbers" part is stupid

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Perelyn-sama

That I agree with, thanks for your feedback

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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 :)