perf: optimize code even further #40
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I measured this by first creating const luhn = require('./index.js') // or index-next
for (let i = 0; i < 1_000_000; i++) luhn('5512345678')And finally used hyperfine to measure: $ hyperfine 'node a.js' 'node b.js'
Benchmark 1: node a.js
Time (mean ± σ): 134.6 ms ± 1.3 ms [User: 131.1 ms, System: 4.3 ms]
Range (min … max): 133.5 ms … 139.6 ms 21 runs
Benchmark 2: node b.js
Time (mean ± σ): 50.9 ms ± 0.6 ms [User: 47.5 ms, System: 3.9 ms]
Range (min … max): 50.1 ms … 53.8 ms 55 runs
Summary
node b.js ran
2.65 ± 0.04 times faster than node a.js |
LinusU
commented
Oct 20, 2023
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| return sum % 10 === 0 | ||
| let index = number.length | ||
| let x2 = true |
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Changing bit to a boolean led to a speed up, and then I thought that x2 was a better name, since it determines wether to multiply the number by 2 or not
LinusU
commented
Oct 20, 2023
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| while (index) { | ||
| const value = number.charCodeAt(--index) - 48 | ||
| if (value < 0 || value > 9) return false |
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The previous implementation had sum turn into NaN which resulted in false being returned in the end, so this should mimic that behaviour
LinusU
commented
Oct 20, 2023
| let bit = 1 | ||
| let sum = 0 | ||
| let value | ||
| const lookup = [0, 2, 4, 6, 8, 1, 3, 5, 7, 9] |
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Renamed this lookup from array since it's a lookup table for (x * 2) % 10 and array felt very generic
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This brings a speed up in all of the test cases I have tried:
5512345678000000000000000042424242424242414242424242424242551234- asd- asd- sa -d as9d0 sad9sd90sa 5678