Benchmark: string split vs indexOf iteration

Script Preparation code:

var str = "123 ".repeat(1000000)

Tests:

split
var split = str.split(" ") var count = 0; for (const s of split) count++;
indexOf walk
var count = 0; var i = 0; while (i >= 0) { count++; i = str.indexOf(" ", i + 1); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
split
indexOf walk

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36 Edg/138.0.0.0

Browser/OS: Chrome 138 on Windows

View result in a separate tab

Test name	Executions per second
split	22.0 Ops/sec
indexOf walk	130.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its test cases.

**Benchmark Definition**

The benchmark is defined by a JSON object that contains:

* `Name`: a unique name for the benchmark
* `Description`: an optional description of the benchmark (in this case, empty)
* `Script Preparation Code`: a JavaScript code snippet that prepares the input data for the benchmark
* `Html Preparation Code`: an optional HTML code snippet that can be used to prepare the environment for the benchmark

In this case, both `Script Preparation Code` and `Html Preparation Code` are empty, which means that no additional setup is required.

**Test Cases**

The benchmark consists of two individual test cases:

1. **"split"`**
	* `Benchmark Definition`: a JavaScript code snippet that uses the `str.split()` method to split a string into an array of substrings.
	* Purpose: To measure the performance of the `str.split()` method.
2. **"indexOf walk"`**
	* `Benchmark Definition`: a JavaScript code snippet that uses a while loop with `str.indexOf()` to iterate over a string and count the number of occurrences of a specific character (`" "`, in this case).
	* Purpose: To measure the performance of the `str.indexOf()` method.

**Library**

In both test cases, the `split()` method is used from the built-in JavaScript Array prototype. No external libraries are required for these tests.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax that are specific to this benchmark.

Now, let's discuss the pros and cons of each approach:

**Split Method (`str.split()`)**

Pros:

* Simple and efficient way to split a string into an array.
* Built-in method with good performance characteristics.

Cons:

* Can be slower than manual iteration for very large strings.
* Creates an intermediate array that may not be desirable in certain scenarios (e.g., memory-intensive applications).

**IndexOf Method (`str.indexOf()`)**

Pros:

* More efficient than split method for small to medium-sized strings.
* Allows for early exit if the character is not found.

Cons:

* Can be slower than manual iteration for very large strings.
* May have performance issues with certain characters or Unicode ranges.

**Other Alternatives**

If you were to rewrite this benchmark, you could consider using alternative approaches, such as:

1. **Regex**: Instead of `str.split()`, you could use a regex replacement approach to achieve the same result. This would likely be slower than `str.split()` but might offer more flexibility for certain use cases.
2. **Manual Iteration**: You could implement manual iteration over the string using a loop, similar to the "indexOf walk" test case. This would allow you to control every aspect of the iteration and optimize for specific scenarios.

In summary, both `str.split()` and `str.indexOf()` have their strengths and weaknesses, and the choice between them depends on the specific requirements of your application and the characteristics of your input data.

Related benchmarks:

string split vs indexOf iteration (version: 0)

Comparing performance of: split vs indexOf walk

Created: one year ago by: Guest

Jump to the latest result

split

indexOf walk

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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