Benchmark: Substring vs string array access

Script Preparation code:

var text = "as dflkjasd flkasjdf";

Tests:

Substring
var a = text.substring(0, 1); var b = text.substring(3, 4); var c = text.substring(10, 11);
String array access
var a = text[0]; var b = text[3]; var c = text[10];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Substring
String array access

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 131 on Android

View result in a separate tab

Test name	Executions per second
Substring	29948014.0 Ops/sec
String array access	29581814.0 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 provided benchmark JSON and explain what is tested, compared, pros, cons, and other considerations.

**Benchmark Definition**

The benchmark measures the performance of two approaches for accessing characters in a string:

1. **Substring**: Using the `substring` method to extract specific character ranges from the input string.
2. **String array access**: Directly indexing into the string using square brackets (`[]`) to access individual characters.

**Options Compared**

Both approaches are compared, but with some differences:

* **Substring**: This approach uses the `substring` method, which returns a new string containing the extracted characters. The length of the substring is specified by the second argument.
* **String array access**: This approach directly accesses the character at the specified index using square brackets (`[]`). There's no need to create a new string like in the substring approach.

**Pros and Cons**

Here are some pros and cons for each approach:

**Substring:**

Pros:

* More flexible, as it allows extracting any range of characters from the input string.
* Can be more efficient if you only need a small portion of the string.

Cons:

* Creates a new string object, which can incur additional memory allocation and garbage collection overhead.
* May have slower performance due to the creation of a new string.

**String array access:**

Pros:

* Directly accesses the character without creating a new string object, reducing memory allocation and garbage collection overhead.
* Typically faster, as it avoids the overhead of string creation.

Cons:

* Only allows accessing individual characters by index; extracting specific ranges may require more operations.
* May not be as flexible as the substring approach.

**Library Used**

There is no explicit library mentioned in the provided benchmark definition. However, note that `substring` and array indexing (`[]`) are built-in JavaScript methods.

**Special JS Feature or Syntax**

None of the approaches rely on any special JavaScript features or syntax beyond what's described in the benchmark definition.

**Other Alternatives**

If you want to explore alternative approaches, consider the following:

1. **Regex**: Using regular expressions (regex) can provide more flexibility for string manipulation and pattern matching. However, it may introduce additional overhead due to the complexity of regex patterns.
2. **String slicing**: Instead of using `substring`, you could use the `slice` method, which returns a new string containing the specified range of characters.

Here's an example of how you might rewrite the benchmark using `slice`:
```javascript
var text = "as dflkjasd flkasjdf";
var a = text.slice(0, 1);
var b = text.slice(3, 4);
var c = text.slice(10, 11);
```
Keep in mind that this approach may have similar performance characteristics to `substring`, as it still involves creating new strings.

I hope this explanation helps you understand the benchmark and its test cases!

Related benchmarks:

Substring vs string array access (version: 0)

Comparing performance of: Substring vs String array access

Created: 4 years ago by: Guest

Jump to the latest result

Substring

String array access

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):