Benchmark: findIndex (reversed) vs findIndex performance (500 items)

Script Preparation code:

var arr = [];
var arrRev = [];
var i = 0;
var j = 0;
var LENGTH = 500;

while (i <= LENGTH) arr[i] = i++;
while (j <= LENGTH) arrRev[j] = j++;

Tests:

findIndex
const index = arr.findIndex(item => item == LENGTH);
findIndex reverse
const index = arrRev.length - arrRev.reverse().findIndex(item => item == LENGTH) - 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 dive into the explanation of the provided JSON benchmark.

**Benchmark Description**
The test aims to measure the performance difference between two approaches to find an element in a reversed array: using the `findIndex` method directly and using the `reverse` method followed by `findIndex`.

**Options Compared**

1. **Direct Approach (findIndex)**: This approach uses the built-in `findIndex` method of the Array prototype, which returns the index of the first occurrence of an element that satisfies a condition.
2. **Indirect Approach (findIndex reverse)**: This approach uses the `reverse` method to reverse the array, and then calls `findIndex` on the reversed array.

**Pros and Cons**

* Direct Approach:
	+ Pros: Fast and efficient, as it's implemented in native code by the browser engine.
	+ Cons: May not work as expected if the condition is false for most elements, leading to unnecessary iterations.
* Indirect Approach:
	+ Pros: Can avoid issues with the direct approach and provide a more predictable result.
	+ Cons: Slower due to the additional method call and array reversal.

**Library/Functionality Used**

The `reverse` method is used in the indirect approach. This method reverses the order of elements in an array and returns the reversed array. It's a standard method in the Array prototype.

**Special JS Feature/Syntax**
There are no special JavaScript features or syntax used in this benchmark.

**Considerations**

* The benchmark measures the performance difference between two approaches, which may depend on the specific use case.
* The `findIndex` method is designed to find an element that satisfies a condition, whereas the indirect approach reverses the array and then searches for the same element. This might lead to different results or behaviors.

**Alternative Approaches**

1. **Using a custom implementation**: Instead of using the built-in `findIndex` method, you could implement your own algorithm to find an element in an array.
2. **Optimizing the condition**: If the condition is often false for most elements, you might consider optimizing it or using a different approach altogether.
3. **Using a library function**: There are libraries like Lodash that provide optimized `findIndex`-like functions with additional features and performance improvements.

Keep in mind that these alternatives may not be relevant to this specific benchmark, but they can be useful for exploring other approaches to similar problems.

Related benchmarks:

findIndex (reversed) vs findIndex performance (500 items) (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):