Benchmark: array.includes vs array.indexOf

Script Preparation code:

var a = Array(10000).fill(undefined).map((_, i) => i);

Tests:

includes
return a.includes(9)
indexOf
return a.indexOf(9)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
includes
indexOf

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36

Browser/OS: Chrome 90 on Windows

View result in a separate tab

Test name	Executions per second
includes	13618852.0 Ops/sec
indexOf	13351942.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net!

The provided JSON represents two benchmark test cases:

**Benchmark Definition**

The `Name` field indicates that we're comparing the performance of `array.includes()` and `array.indexOf()`. The `Description` is empty, which means there's no descriptive text for this benchmark.

**Script Preparation Code**

This code snippet creates an array `a` with 10,000 elements, filling them with `undefined`, and then maps over it to generate indices (`i`). This will be used as the input array for our benchmarks.

**Html Preparation Code**

There's no HTML preparation code provided, which means we're not generating any specific HTML structure to run our benchmarks on.

Now, let's break down the individual test cases:

1. **Benchmark Definition: "return a.includes(9)"**
This line of code checks if the number 9 exists within the array `a`. The `includes()` method searches for the specified value (`9`) in the array and returns `true` if found.
2. **Benchmark Definition: "return a.indexOf(9)"**
This line of code attempts to find the index of the number 9 within the array `a`. The `indexOf()` method returns the index of the first occurrence of the specified value (`9`) or -1 if not found.

**What are we comparing?**

We're comparing the performance ( execution time) of two different approaches:

1. **`array.includes()`**: This method searches for a single element in the array and returns `true` if found, otherwise `false`. It's generally faster than `indexOf()`.
2. **`array.indexOf()`**: This method attempts to find the index of a specific element in the array. If the element is not found, it returns -1.

**Pros and Cons**

* **`array.includes()`**:
	+ Pros: Generally faster than `indexOf()`, as it can return immediately if the element is found.
	+ Cons: May perform an unnecessary iteration over the entire array if the element is not found.
* **`array.indexOf()`**:
	+ Pros: Can provide a meaningful index value even if the element is not found.
	+ Cons: Generally slower than `includes()`, as it needs to iterate over the entire array to find the first occurrence.

**Library and Special Features**

Neither of these benchmark test cases uses any external libraries or special JavaScript features. They're focused solely on comparing the performance of the two built-in methods.

**Other Alternatives**

If you want to explore other approaches, here are a few alternatives:

* **`array.prototype.includes()`**: This is the recommended method in modern JavaScript (ES6+). It's generally faster than `includes()`, but may have slightly different behavior if used with older browsers.
* **`binarySearch()`**: If you're willing to implement your own binary search algorithm, it can be significantly faster than the built-in methods. However, this approach requires additional logic and is not as straightforward.

Keep in mind that these alternative approaches might change depending on the specific requirements of your project or use case.

That's a summary of the JavaScript microbenchmarking example on MeasureThat.net!

Related benchmarks:

array.includes vs array.indexOf (version: 0)

Comparing performance of: includes vs indexOf

Created: one year ago by: Guest

Jump to the latest result

includes

indexOf

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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