41 lines
1.5 KiB
Markdown
41 lines
1.5 KiB
Markdown
---
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title: Most performant function
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tags: function
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expertise: advanced
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cover: blog_images/lake-runner.jpg
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firstSeen: 2018-02-14T13:38:45+02:00
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lastUpdated: 2020-10-21T21:54:53+03:00
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---
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Returns the index of the function in an array of functions which executed the fastest.
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- Use `Array.prototype.map()` to generate an array where each value is the total time taken to execute the function after `iterations` times.
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- Use the difference in `performance.now()` values before and after to get the total time in milliseconds to a high degree of accuracy.
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- Use `Math.min()` to find the minimum execution time, and return the index of that shortest time which corresponds to the index of the most performant function.
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- Omit the second argument, `iterations`, to use a default of `10000` iterations.
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- The more iterations, the more reliable the result but the longer it will take.
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```js
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const mostPerformant = (fns, iterations = 10000) => {
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const times = fns.map(fn => {
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const before = performance.now();
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for (let i = 0; i < iterations; i++) fn();
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return performance.now() - before;
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});
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return times.indexOf(Math.min(...times));
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};
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```
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```js
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mostPerformant([
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() => {
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// Loops through the entire array before returning `false`
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[1, 2, 3, 4, 5, 6, 7, 8, 9, '10'].every(el => typeof el === 'number');
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},
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() => {
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// Only needs to reach index `1` before returning `false`
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[1, '2', 3, 4, 5, 6, 7, 8, 9, 10].every(el => typeof el === 'number');
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}
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]); // 1
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```
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