Benchmark: array index vs substring

Script Preparation code:

var dni = "12345678-9"

Tests:

array
var a = dni[3] var b = dni [8]
subs
var c = dni.substring(dni.length -1) var d = dni.substring(dni.length -6)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array
subs

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
array	9870242.0 Ops/sec
subs	4956867.5 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark measures the performance difference between accessing an array element using indexing (`dni[3]` and `dni[8]`) versus using the `substring()` method to extract a substring from the string `dni`.

**Options Compared**

Two approaches are compared:

1. **Array Indexing**: Directly accessing an element in the `dni` array using its index.
2. **Substring Method**: Using the `substring()` method to extract a substring from `dni`, starting from a specific position and length.

**Pros and Cons of Each Approach**

* **Array Indexing**:
	+ Pros:
		- Faster access time, as it directly accesses an element in memory.
		- More readable code, especially for those familiar with array indexing.
	+ Cons:
		- May lead to out-of-bounds errors if the index is not validated.
		- Less flexible, as it's limited to accessing elements by their index.
* **Substring Method**:
	+ Pros:
		- More flexible, allowing for substring extraction from any position in the string.
		- Reduces the risk of out-of-bounds errors, as `substring()` validates its arguments.
	+ Cons:
		- Slower access time, due to the overhead of creating a new substring object and searching for the target character.
		- Less readable code, especially for those unfamiliar with the `substring()` method.

**Library and Special JavaScript Features**

In this benchmark, no specific library is used. However, the use of array indexing is a built-in JavaScript feature that has been part of the language since its early days. The `substring()` method, on the other hand, is also a built-in method in JavaScript.

**Other Considerations**

* Performance: As mentioned earlier, access time and memory usage are critical factors. Array indexing tends to be faster but more memory-intensive, while substring extraction can be slower due to the overhead of creating new objects.
* Code Readability: The choice between array indexing and substring extraction often comes down to code readability. Some developers prefer the simplicity of array indexing, while others find the `substring()` method more readable for its explicit nature.

**Alternatives**

If you were to write this benchmark using a different language or approach, some alternatives could be:

* Using a library like `string-polyfill` to provide the `substring()` method in older browsers or environments that don't support it natively.
* Implementing a custom substring extraction function, which could potentially be faster but also less readable.
* Comparing performance with different string concatenation methods (e.g., using template literals vs. traditional string concatenation).

In summary, this benchmark provides a simple yet informative comparison between two common ways of accessing elements in JavaScript strings. By understanding the pros and cons of each approach, developers can make informed decisions about which method to use depending on their specific needs and requirements.

Related benchmarks:

array index vs substring (version: 0)

array index vs substring

Comparing performance of: array vs subs

Created: 2 years ago by: Guest

Jump to the latest result

array

subs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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