Benchmark: replace vs substring 2

replace vs substring 2 (version: 0)

Test the performance of replace() vs substring() vs slice() when replacing a char at the beginning of a (in this case uri query-)string that may or may not be there. Added the combined brackets[ ] + substr() method, since it's always the first char we wan't to pop off. Inspired by https://jsperf.com/replace-or-substr. Note: could not get 'let' and 'const' to work. Well, too bad...

Comparing performance of: substring and substring vs replace inline regex

Created: one year ago by: Guest

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Script Preparation code:

var strIn = 'index.html';
var strOut = '';

Tests:

substring and substring
index = strIn.indexOf('.html') strOut = strIn.substr(index);
replace inline regex
strOut = strIn.replace('.html', "");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
substring and substring
replace inline regex

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/116.0

Browser/OS: Firefox 116 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
substring and substring	22600226.0 Ops/sec
replace inline regex	21695590.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Main Goal:**
The goal of this benchmark is to compare the performance of three different string manipulation methods:

1. `substring()`
2. `replace()` (with and without regular expressions)
3. A custom method that combines `substr()` with brackets (`[ ]`)

**Benchmark Scope:**

* The input string `strIn` is set to `'index.html'`.
* The benchmark tests the performance of each method when replacing a character at the beginning of the string, which may or may not be present.

**Options Compared:**

1. **substring()**: This method returns a new string that starts from the specified index and continues to the end of the string.
2. **replace() (with inline regex)**: This method replaces all occurrences of the specified pattern in the string with another string. In this case, it's replacing the dot (`.`) followed by `html`.
3. **Custom method with [ ] + substr()**: This method uses the `substr()` function to extract a subset of characters from the input string and then concatenates brackets around the extracted substring.

**Pros and Cons:**

1. **substring()**:
	* Pros: Simple, efficient.
	* Cons: May be slower if the index is large or the string is very long.
2. **replace() (with inline regex)**:
	* Pros: Flexible, can handle complex patterns.
	* Cons: May be slower due to the overhead of regular expressions, especially for simple cases like this one.
3. **Custom method with [ ] + substr()**:
	* Pros: Simple, efficient.
	* Cons: Less readable and maintainable than other methods.

**Library Used:**
None explicitly mentioned in the benchmark definition or test cases. However, `substr()` is a built-in JavaScript function.

**Special JS Features/Syntax:**
There's no explicit mention of any special JavaScript features or syntax being used beyond the standard methods and libraries.

**Alternatives:**

If you wanted to optimize this benchmark further, you could consider:

1. Using more efficient string manipulation libraries like ICU (International Components for Unicode).
2. Implementing the custom method using a different approach, such as using `String.prototype.indexOf()` and `String.prototype.slice()`.
3. Adding more test cases to cover edge cases or variations on these methods.

Keep in mind that the current benchmark is already well-structured and provides valuable insights into the performance characteristics of each method.

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