var test = [ { id: 1, name: 1, }, { id: 2, name: 12, }, { id: 3, name: 13, }, { id: 4, name: 14, }, { id: 5, name: 15, }, { id: 6, name: 16, }]new Map(test.flatMap(c => { if (c.id < 3) { return [] } return [[c.id, c]]}))new Map(test.filter(c => { return c.id >= 3}).map(el => [el.id, el]))--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| flatmap | |
| filter.map |
| Test name | Executions per second |
|---|---|
| flatmap | 773396.2 Ops/sec |
| filter.map | 2795218.0 Ops/sec |
Let's break down the provided benchmark JSON and explain what's being tested.
Benchmark Definition
The benchmark compares two approaches to create a new Map from an array:
flatMap: A method introduced in ECMAScript 2017 (ES7) that creates a new array by calling a provided function for each element of the original array.filter + map: A combination of two methods: filter, which creates a new array with only the elements that pass a test, and map, which applies a specified function to each element in the resulting array.Options Compared
The benchmark compares the performance of these two approaches:
flatMapfilter + mapPros and Cons
filter + map: Pros:Library and Special JavaScript Features
There are no libraries used in this benchmark. However, the flatMap method is a modern JavaScript feature that was introduced in ES7.
Other Considerations
When choosing between these approaches, consider the trade-offs between readability, conciseness, and performance. If you need to support older browsers or environments that don't support ES7 features, filter + map might be a better choice. However, if you're targeting modern browsers and want more concise code, flatMap could be a better option.
Other Alternatives
If you're looking for alternative approaches to create a new Map from an array, consider:
Array.prototype.reduce(): This method can achieve similar results as flatMap or filter + map, but with a more functional programming style.Array.prototype.forEach() and creating a new Map manually: This approach involves iterating over the original array and adding entries to a new Map using the forEach method. While not as concise as flatMap or filter + map, it can be an alternative solution.Keep in mind that these alternatives might have different performance characteristics and trade-offs, so consider the specific requirements of your use case when choosing an approach.
