Benchmark: Map speed test - MeasureThat.net

Tests:

Map 1
function a(arr){ return arr ? arr.map((item) => item) : []; } let b = a(); let c = a([1,2,3])
Map 2
function a(arr){ return (arr || []).map((item) => item); } let b = a(); let c = a([1,2,3])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map 1
Map 2

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Measuring the performance of JavaScript microbenchmarks is crucial to understand how different browsers and environments execute JavaScript code efficiently.

The provided benchmark definition json represents a simple test case that measures the speed of two approaches for creating an array from another array using the `map` method. Here's a breakdown of what each approach does, their pros and cons, and other considerations:

1. **Approach 1:** `arr ? arr.map((item) => item) : []`
	* This approach uses the Elvis operator (`?`) to check if `arr` is truthy. If it is, it maps over `arr`, returning a new array with each element unchanged.
	* Pros:
		+ Concise and readable code.
		+ Avoids potential errors when dealing with null or undefined values.
	* Cons:
		+ May be slower due to the Elvis operator evaluation.
2. **Approach 2:** `(arr || []).map((item) => item)`
	* This approach uses the OR operator (`||`) to return an empty array if `arr` is falsy, and then maps over it.
	* Pros:
		+ Faster since it avoids the Elvis operator evaluation.
	* Cons:
		+ May throw errors if `arr` is null or undefined.

Other considerations:

* **Null and undefined checks:** Both approaches assume that the input array will always have some elements. If this assumption is not valid, additional checks should be added to handle edge cases.
* **Browser differences:** Different browsers may optimize or execute JavaScript code differently, affecting benchmark results. This is why it's essential to test on multiple platforms and browsers.

The `Map` function in JavaScript uses a technique called " lazy mapping" , which is faster than the approach 1. But this technique also makes both of the approaches we are considering have better performance when compared to another common method `(function(arr) { return arr.reduce((item, currItem) => item.concat(currItem)); };)`.

Another alternative approach for map function would be using `Array.prototype.filter()` and then `concat()`, but this is slower than both of our methods:

`let c = Array.from(a()).filter(item => true).concat([]);`

However, all three approaches we are considering will throw an error if the input array contains a non-iterable value. To handle this case, additional checks should be added to ensure the input array only contains iterables.

Now let's look at the individual test cases:

* **Test Case 1:** "Map 1"
	+ The benchmark definition function `a` takes an array as input and returns a new array with each element unchanged.
	+ The raw UA string for this test case is from Firefox 82 on Windows.
	+ The `ExecutionsPerSecond` value indicates how many times the function was executed per second during the test.
* **Test Case 2:** "Map 2"
	+ The benchmark definition function `a` takes an array as input and returns a new array with each element unchanged, but uses the OR operator to check for falsy inputs.
	+ The raw UA string for this test case is also from Firefox 82 on Windows.
	+ The `ExecutionsPerSecond` value indicates how many times the function was executed per second during the test.

By comparing these two test cases, we can determine which approach is faster in different browsers and environments.

Related benchmarks:

Map speed test (version: 0)

Comparing performance of: Map 1 vs Map 2

Created: 5 years ago by: Guest

Jump to the latest result

Map 1

Map 2

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):