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

Script Preparation code:

var str = 'foo bar baz';
var str_array = str.split('');
var noop = Function.prototype;

Tests:

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is designed to compare three different methods for accessing the first character of a string: using an array index (`str_array[0]`), using the `charAt()` method (`str.charAt(0)`), and using the `slice()` method (`str.slice(0, 1)`).

**Options being compared**

The benchmark is comparing the performance of these three methods:

* **Array Index**: Using an array index to access the first character of a string.
* **charAt()**: Using the `charAt()` method to access a single character in a string.
* **slice()**: Using the `slice()` method to extract a subset of characters from a string.

**Pros and Cons**

Here are some pros and cons for each approach:

* **Array Index**:
	+ Pros: Simple, straightforward, and widely supported. It's likely to be fast because it involves simple arithmetic.
	+ Cons: May not be the most efficient way to access individual characters in large strings.
* **charAt()**:
	+ Pros: Designed specifically for accessing individual characters, making it a good choice for this benchmark.
	+ Cons: May have some overhead due to the method call and parameter passing.
* **slice()**:
	+ Pros: Can be used to extract substrings, not just single characters. It's also designed for performance.
	+ Cons: May create an intermediate array, which could be slower than direct array indexing.

**Library**

In this benchmark, no libraries are explicitly mentioned. However, it's worth noting that `Function.prototype` is being used in the script preparation code, which is a built-in part of JavaScript.

**Special JS feature or syntax**

None are being tested specifically for their performance; however, we can note that these methods are all valid ways to access individual characters in strings, as per the ECMAScript standard.

**Other alternatives**

If you were to add more alternatives, some other options might include:

* Using `substr()` instead of `slice()`
* Using `substring()` instead of `slice()`
* Using a regular expression (`/[a-zA-Z]/`) instead of any of the above methods
* Using a custom implementation for accessing individual characters (e.g., using bit manipulation)

Keep in mind that these alternatives would likely have different performance characteristics and might not be relevant to this specific benchmark.

**Benchmark preparation code**

The script preparation code creates a sample string `str` containing three words, splits it into an array of individual characters (`str_array`), and defines a no-op function (`noop`) on the `Function.prototype`.

**Test cases**

Each test case consists of a single execution statement:

* `character index`: Accesses the first character of `str_array` using an array index.
* `charAt()`: Accesses the first character of `str` using the `charAt()` method.
* `slice()`: Accesses the first character of `str` using the `slice()` method.

These test cases are designed to compare the performance of each method for accessing a single character in a string.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36

Browser/OS: Chrome 106 on Linux

View result in a separate tab

Test name	Executions per second
character index	6868791.0 Ops/sec
charAt()	6597796.5 Ops/sec
slice()	6479727.5 Ops/sec

Related benchmarks:

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

Compare methods for testing string's beggining character.

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

Created: 2 years ago by: Guest

Jump to the latest result

character index

charAt()

slice()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):