Benchmark: findIndex (reversed) vs findIndex performance

Script Preparation code:

var arr = [];
var arrRev = [];
var i = 0;
var j = 0;

while (i <= 1E5) arr[i] = i++;
while (j <= 1E5) arrRev[j] = j++;

Tests:

findIndex
const index = arr.findIndex(item => item == 1E5);
findIndex reverse
const index = arrRev.length - arrRev.reverse().findIndex(item => item == 1E5) - 1;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
findIndex
findIndex reverse

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark and explain what's being tested, compared, and other considerations.

**Benchmark Definition**

The benchmark measures the performance of two approaches to find an index in an array: using `findIndex` directly and using `reverse`, finding the length of the reversed array, and then subtracting 1 from the result.

**Script Preparation Code**

The script prepares two arrays: `arr` and `arrRev`. The first array is populated with numbers from 0 to 100,000, where each number is assigned to an index equal to its value (using `i++`). The second array is populated in reverse order using a similar approach. This creates two arrays of the same length.

**Html Preparation Code**

There is no HTML preparation code provided.

**Individual Test Cases**

The benchmark consists of two test cases:

1. **findIndex**: This test case uses the `findIndex` method directly on the original array (`arr`) to find the index of the first occurrence of the value 100,000.
2. **findIndex reverse**: This test case uses a combination of methods to achieve the same result as the first test case:
	* Reverse the second array (`arrRev`) using `reverse()`.
	* Find the length of the reversed array using `length`.
	* Subtract 1 from the length to get the index.
3. **findIndex reverse**: This test case uses a combination of methods to achieve the same result as the first test case:
	* Reverse the second array (`arrRev`) using `reverse()`.
	* Find the index of the value 100,000 in the reversed array using `findIndex`.

**Library Used**

There is no library explicitly mentioned in the benchmark definition. However, the `reverse()` method and the `findIndex` method are built-in JavaScript methods.

**Pros and Cons of Each Approach**

1. **Directly using `findIndex`**:
	* Pros: Simple and concise code.
	* Cons: May be slower due to the overhead of searching the array.
2. **Using `reverse`, finding length, and subtracting 1**: (Both test cases use this approach)
	* Pros: Can avoid potential issues with negative indices or arrays with duplicate values.
	* Cons:
		+ More complex code compared to using `findIndex` directly.
		+ May have additional overhead due to reversing the array.

**Other Considerations**

* The benchmark measures execution per second, which is a good indicator of performance. However, it's essential to note that this metric can be influenced by various factors such as CPU speed, memory usage, and JavaScript engine optimizations.
* The use of `const` and the absence of any error handling code in the script preparation code simplifies the benchmarking process but may not accurately represent real-world scenarios.

**Alternatives**

If you were to run this benchmark with different approaches or modifications, some alternatives could be:

* Using `indexOf` instead of `findIndex`
* Adding a check for null values before calling `findIndex` or `indexOf`
* Using a more efficient data structure, such as a sparse array or a Set
* Optimizing the script preparation code to reduce memory allocation and garbage collection overhead
* Running the benchmark with different input sizes or distributions

Related benchmarks:

findIndex (reversed) vs findIndex performance (version: 0)

Measuring which is faster

Comparing performance of: findIndex vs findIndex reverse

Created: 2 years ago by: Guest

Jump to the latest result

findIndex

findIndex reverse

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):