Benchmark: String indexer vs substring

Script Preparation code:

var value = "The quick brown fox jumps over the lazy dog";
var len = value.length

Tests:

indexer
for(var i = 0 ; i < len; i++) var c = value[i];
substring
for(var i = 0 ; i < len; i++) var c = value.substring(i,1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexer
substring

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

Browser/OS: Chrome 110 on Linux

View result in a separate tab

Test name	Executions per second
indexer	247499.1 Ops/sec
substring	256173.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition:**

The benchmark is designed to compare two approaches for extracting individual characters from a string: using an index-based approach (`"indexer"`) versus using the `substring()` method (`"substring"`).

**Script Preparation Code:**
```javascript
var value = "The quick brown fox jumps over the lazy dog";
var len = value.length;
```
This code sets up a sample string `value` with 36 characters and assigns its length to a variable `len`.

**Html Preparation Code:** (empty)

There is no HTML preparation code provided, which means this benchmark only tests the JavaScript execution.

**Test Cases:**

We have two individual test cases:

1. `"indexer"`:
```javascript
for(var i = 0 ; i < len; i++)
  var c = value[i];
```
This code uses a traditional `for` loop to iterate over the characters of the string, assigning each character to a variable `c`.

2. `"substring"`:
```javascript
for(var i = 0 ; i < len; i++)
  var c = value.substring(i,1);
```
This code uses the `substring()` method to extract individual characters from the string, starting from index `i` and taking only one character (`length 1`). Note that this approach will throw an error if `i` is equal to `len`, since it's out of bounds.

**Pros and Cons:**

* **Index-based approach ("indexer")**:
	+ Pros:
		- Efficient, as it directly accesses the character at index `i`.
	+ Cons:
		- May throw an error if `i` is equal to `len`, which can lead to unexpected behavior.
* **Substring approach ("substring")**:
	+ Pros:
		- Does not require manual indexing, making it more robust.
	+ Cons:
		- Less efficient than the index-based approach, as it creates a new string slice.

**Library:**

There is no specific library mentioned in this benchmark. However, if we consider `substring()` method, it's an inherent part of the ECMAScript standard and widely supported by most browsers.

**Special JS Feature or Syntax:**

None explicitly mentioned in this benchmark.

**Other Alternatives:**

If you want to test other approaches for extracting individual characters from a string, here are some alternatives:

* Using `slice()` method: `for(var i = 0 ; i < len; i++) var c = value.slice(i,1);`
* Using regular expressions: `for(var i = 0 ; i < len; i++) var regex = new RegExp('^(?=.){i}'); var match = regex.exec(value); if (match) var c = match[0];`

Keep in mind that these alternatives might have different performance characteristics or behaviors compared to the index-based and substring approaches.

Overall, this benchmark provides a useful comparison between two common approaches for extracting individual characters from a string.

Related benchmarks:

String indexer vs substring (version: 0)

Comparing performance of: indexer vs substring

Created: one year ago by: Guest

Jump to the latest result

indexer

substring

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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