Benchmark: replace vs substring2w22

replace vs substring2w22 (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: 2 years ago by: Guest

Go to the latest result

Script Preparation code:

var strIn = 'message-content-1182546500266500126';
var strOut = '';

Tests:

substring and substring
strOut = strIn.substr(16);
replace inline regex
strOut = strIn.replace('message-content-', "");

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: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Windows

View result in a separate tab

substring and substring

14.6M/s

replace inline regex

11.9M/s

View exact numbers

Test name	Executions per second
✓ substring and substring	14,635,665 Ops/sec
replace inline regex	11,879,126 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 of three different methods for replacing a character at the beginning of a string: `replace()`, `substring()` with a substring, and a custom approach using `[ ]` combined with `substring()`. The goal is to determine which method is the fastest.

**Options Compared**

1. **replace():** This method uses regular expressions to replace the specified substring with another substring.
2. **substring():** This method extracts a section of the string that starts at the specified index and has a specified length.
3. **Custom approach:** `[ ]` combined with `substring()` is used to extract the first character from the string.

**Pros and Cons**

1. **replace():**
	* Pros: Fast, widely supported, and easy to use for simple replacements.
	* Cons: Can be slow for large strings due to regular expression parsing, and may not be suitable for complex replacements.
2. **substring():**
	* Pros: Can be faster than `replace()` for small strings, and allows for more control over the extracted section.
	* Cons: May be slower for large strings due to string copying, and requires careful indexing to avoid errors.
3. **Custom approach:**
	* Pros: Fast and efficient for extracting the first character, as it only requires a single operation.
	* Cons: Less intuitive than `replace()` or `substring()`, may require more code to implement.

**Library Usage**

The custom approach uses the `[ ]` operator, which is part of JavaScript's array syntax. This allows us to extract the first element from an array (or in this case, a string) using the index 0.

**Special JS Feature/Syntax**

* `let` and `const`: While not used in this benchmark, they are special keywords in JavaScript that allow for block-scoped variable declarations. However, their use is restricted by MeasureThat.net's testing environment.
* Regular expressions: The `replace()` method uses regular expressions to replace the specified substring.

**Other Alternatives**

1. **String.prototype.replace():** This is a more efficient version of the `replace()` method that returns a new string with the replaced characters, rather than modifying the original string.
2. **String.prototype.slice():** This method extracts a section of the string using slicing, which can be faster for large strings.

In summary, the benchmark compares three different approaches to replacing a character at the beginning of a string: `replace()`, `substring()` with a substring, and a custom approach using `[ ]` combined with `substring()`. The choice of method depends on the specific use case and performance requirements.