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30-seconds-of-code/snippets/mostPerformant.md
Isabelle Viktoria Maciohsek ce48fffb4d Update snippet descriptions
2020-10-21 21:54:53 +03:00

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---
title: mostPerformant
tags: function,advanced
---
Returns the index of the function in an array of functions which executed the fastest.
- Use `Array.prototype.map()` to generate an array where each value is the total time taken to execute the function after `iterations` times.
- Use the difference in `performance.now()` values before and after to get the total time in milliseconds to a high degree of accuracy.
- 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.
- Omit the second argument, `iterations`, to use a default of `10000` iterations.
- The more iterations, the more reliable the result but the longer it will take.
```js
const mostPerformant = (fns, iterations = 10000) => {
const times = fns.map(fn => {
const before = performance.now();
for (let i = 0; i < iterations; i++) fn();
return performance.now() - before;
});
return times.indexOf(Math.min(...times));
};
```
```js
mostPerformant([
() => {
// Loops through the entire array before returning `false`
[1, 2, 3, 4, 5, 6, 7, 8, 9, '10'].every(el => typeof el === 'number');
},
() => {
// Only needs to reach index `1` before returning `false`
[1, '2', 3, 4, 5, 6, 7, 8, 9, 10].every(el => typeof el === 'number');
}
]); // 1
```