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();

Historical Performance Data aggregated from 44 community runs

Desktop Results:

Chrome 24 runs

slice()

15.5M/s

character index

15.5M/s

charAt()

15.4M/s

at()

15.1M/s

View exact numbers

✓ slice(): 15,478,131 ops/sec
• character index: 15,472,215 ops/sec
• charAt(): 15,379,526 ops/sec
• at(): 15,066,350 ops/sec

Firefox 15 runs

character index

134.1M/s

charAt()

125.8M/s

slice()

125.1M/s

at()

79.5M/s

Fastest: character index (1.7x faster)

View exact numbers

✓ character index: 134,132,968 ops/sec
• charAt(): 125,789,600 ops/sec
• slice(): 125,126,560 ops/sec
• at(): 79,488,272 ops/sec

Mobile Results:

Chrome 5 runs

charAt()

3.9M/s

slice()

3.9M/s

character index

3.8M/s

at()

3.8M/s

View exact numbers

✓ charAt(): 3,888,161 ops/sec
• slice(): 3,874,562 ops/sec
• character index: 3,849,959 ops/sec
• at(): 3,786,473 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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: 14 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36 Edg/150.0.0.0

Browser/OS: Chrome 150 on Windows

View result in a separate tab

character index

240.8M/s

slice()

239.4M/s

charAt()

238.4M/s

at()

116.8M/s

View exact numbers

Test name	Executions per second
✓ character index	240,844,848 Ops/sec
slice()	239,383,312 Ops/sec
charAt()	238,374,928 Ops/sec
at()	116,778,632 Ops/sec

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

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: 4 years ago by: Registered User

Go to the latest result

character index

charAt()

slice()

at()

Historical Performance Data aggregated from 44 community runs

Desktop Results:

Chrome 24 runs

Firefox 15 runs

Mobile Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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: 4 years ago by: Registered User

Go to the latest result

character index

charAt()

slice()

at()

Historical Performance Data aggregated from 44 community runs

Desktop Results:

Chrome 24 runs

Firefox 15 runs

Mobile Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

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