Benchmark: char index vs charAt() vs slice() vs at()

Script Preparation code:

var str = 'foo bar baz';
var noop = Function.prototype;

Tests:

character index
if (str[0] === 'f') noop();
charAt()
if (str.charAt(0) === 'f') noop();
slice()
if (str.slice(0, 1) === 'f') noop();
at()
if (str.at(0) === 'f') noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
character index
charAt()
slice()
at()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 134 on Android

View result in a separate tab

Test name	Executions per second
character index	61872456.0 Ops/sec
charAt()	62917224.0 Ops/sec
slice()	53101828.0 Ops/sec
at()	43317256.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Overview**

The provided JSON represents a benchmark test case named "char index vs charAt() vs slice() vs at()" on the MeasureThat.net website. The goal is to compare the performance of four different methods for testing the first character of a string:

1. Character indexing (`str[0]`)
2. `charAt()` method
3. String slicing with a starting index (`str.slice(0, 1)`)
4. Array-like object indexing (`at()`)

**Options Comparison**

The four options are compared in terms of their performance and execution speed. Here's a brief overview of each option:

1. **Character Indexing (`str[0]`)**: This method involves directly accessing the first character of the string using square brackets.
	* Pros: Simple, straightforward approach.
	* Cons: May not be as efficient as other methods, especially for larger strings.
2. **`charAt()` Method**: The `charAt()` method is a built-in JavaScript function that returns the character at a specified index in a string.
	* Pros: Standardized and widely supported.
	* Cons: May incur additional overhead due to function call and parameter passing.
3. **String Slicing with Indexing (`str.slice(0, 1)`)**: This method involves slicing a subset of characters from the beginning of the string using `slice()`.
	* Pros: Efficient for small strings or when only needing a portion of the character set.
	* Cons: May not be suitable for larger strings due to performance overhead.
4. **Array-like Object Indexing (`at()`)**: This method is less common and might not be supported by all browsers or environments.
	* Pros: Might offer better performance for specific use cases, but its adoption is limited.
	* Cons: May not work in older browsers or environments that don't support the `at()` function.

**Library and Special Features**

There are no external libraries involved in this benchmark. However, it's essential to note that some browsers might have additional features or optimizations for string manipulation, such as Unicode support or caching mechanisms.

**Test Cases**

Each test case represents a separate instance of the benchmark, focusing on a specific method:

1. **Character Indexing**: Tests the direct access of the first character using square brackets.
2. **`charAt()` Method**: Evaluates the performance of the `charAt()` function for string manipulation.
3. **String Slicing**: Assesses the efficiency of slicing a subset of characters from the beginning of the string.
4. **Array-like Object Indexing**: (Less common) Tests the usage and performance of array-like object indexing for character access.

**Benchmark Results**

The provided benchmark results show the execution speeds for each test case, measured in executions per second (`ExecutionsPerSecond`). The top-performing method varies across different browsers and devices, but generally, `charAt()` and character indexing are competitive. Keep in mind that this data is specific to a single browser version (Chrome 128) on a desktop platform.

**Alternatives**

If you're looking for alternative benchmarking tools or approaches, consider the following:

1. **jsperf**: A popular JavaScript performance testing tool.
2. **Benchmark.js**: A lightweight and extensible benchmarking library.
3. **WebPageTest**: A comprehensive performance evaluation tool that can include JavaScript benchmarks.

When choosing a benchmarking tool or approach, ensure it aligns with your specific use case, browser support, and performance requirements.

I hope this explanation helped!

Related benchmarks:

char index vs charAt() vs slice() vs at() (version: 0)

Compare methods for testing string's beginning character.

Comparing performance of: character index vs charAt() vs slice() vs at()

Created: 2 years ago by: Registered User

Jump to the latest result

character index

charAt()

slice()

at()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):