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Cover image for 1 line of code: How to create a range array
Martin Krause
Martin Krause

Posted on • Edited on

1 line of code: How to create a range array

#javascript #webdev #performance #codequality 
const createRange = (from, to) => Array.from({ length: to - from + 1 }, (_, i) => from + i);
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Returns a new array with numeric items in the given range.

Optimised code (Benchmark) 

const createRange = (a, b, sign = Math.sign(b - a)) =>  Array(Math.abs(b - a + sign)).fill().map((_, i) => a + sign * i);
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The repository & npm package

You can find the all the utility functions from this series at github.com/martinkr/onelinecode
The library is also published to npm as @onelinecode for your convenience.

The code and the npm package will be updated every time I publish a new article.

Follow me on Twitter: @martinkr and consider to buy me a coffee

Photo by zoo_monkey on Unsplash

Top comments (10)

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pengeszikra profile image
Peter Vivo • • Edited 
const makeRange = (a, b, sign = Math.sign(b - a)) => 
  Array(Math.abs(b - a + sign))
    .fill()
    .map((_, i) => a + sign * i)
  ;

// makeRange(3, -4) -> [3, 2, 1, 0, -1, -2, -3, -4]
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Maybe can write in single line.

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martinkr profile image
Martin Krause •

Check the Benchmark). I updated the article and the code with your solution.

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martinkr profile image
Martin Krause •

Hi,
thank you for your contribution.
Nice code - I'll set up a benchmark.and compare all suggestions so we can find the fastest one.
Cheers!

Cheers!

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jonrandy profile image
Jon Randy 🎖️ •

Not really a one-liner, but it is possible to make a range syntax like this in JS:

1[to(6)]   // [1, 2, 3, 4, 5, 6]
9[to(5)]   // [9, 8, 7, 6, 5]
2[to(8, {step: 2})]   // [2, 4, 6, 8]
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If you want to know how - take a look at my post

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martinkr profile image
Martin Krause •

Amazing series!

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jonrandy profile image
Jon Randy 🎖️ •

More to come when I have some time: String and Array extensions

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martinkr profile image
Martin Krause •

nice!

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gaoryrt profile image
gaoryrt • 
const createRange = (from, to) => [...Array(to + 1).keys()].slice(from);
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martinkr profile image
Martin Krause •

Check the Benchmark) if you like.

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martinkr profile image
Martin Krause •

Hi,
thank you for your contribution.
Nice code - I'll set up a benchmark.

Cheers!

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