Benchmark: 3xif||regexp2 - MeasureThat.net

3xif||regexp2 (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: `if vs regex vs rexex2`

Created: 5 years ago by: Guest

Go to the latest result

Script Preparation code:

var strIn = 'https://www.data-xata.com/all-servers.html/////';

Tests:

if
if(strIn.endsWith('.html')) {} if(strIn.endsWith('.htm')) {} if(strIn.endsWith('/')) {} strIn.substring(0,strIn.length-5)
regex
/(\.html|\.htm|\/)$/.test(strIn) strIn.substring(0,strIn.length-5)
rexex2
/(\.html|\.htm|\/)$/.test(strIn) strIn.replace(/\/+$|\.html?$/, '')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
if
regex
rexex2

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 15_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.6 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 15 on iOS 15.6

View result in a separate tab

rexex2

26.6M/s

regex

17.0M/s

7.9M/s

View exact numbers

Test name	Executions per second
✓ rexex2	26,603,770 Ops/sec
regex	17,003,202 Ops/sec
if	7,880,324 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its test cases.

**Benchmark Overview**

The goal of this benchmark is to compare the performance of three different approaches for replacing a character at the beginning of a string in JavaScript:

1. `if`-based approach
2. Regular expression (`/regex`) approach
3. Combined bracket and substring (`rexex2`) approach

**Test Cases**

There are three test cases, each testing one of these approaches.

### Test Case 1: `if`

This test case uses the `if` statement to check if a string ends with `.html`, `.htm`, or `/`. If it does, the string is then truncated using `substring(0, strIn.length-5)`.

**Library Used:** None (built-in JavaScript)

**Special JS Feature/Syntax:** The use of `endsWith()` method, which is not supported in older browsers. This test case may not run on Internet Explorer or other older browsers that do not support this method.

### Test Case 2: `/regex`

This test case uses a regular expression (`/\\.html|\\.htm|\\/$/`) to check if the string ends with `.html`, `.htm`, or `/`. If it does, the string is then truncated using `substring(0, strIn.length-5)`.

**Library Used:** Regular Expressions

The use of regular expressions can be slower than other approaches, as they require more processing power and may incur additional overhead due to the parsing of the regex pattern.

### Test Case 3: `/rexex2`

This test case uses a combined approach that first checks if the string ends with `.html`, `.htm`, or `/` using a regular expression (`/\\.html|\\.htm|\\/$/`). If it does, the `replace()` method is used to remove any trailing characters from the string.

**Library Used:** Regular Expressions

This approach combines the benefits of both regular expressions and the `replace()` method. However, it may still incur additional overhead due to the parsing of the regex pattern.

**Pros and Cons**

* **`if`-based approach:**
	+ Pros: Simple, fast, and efficient.
	+ Cons: May not work in older browsers that do not support `endsWith()` method.
* **/regex approach:**
	+ Pros: Can handle more complex patterns and edge cases.
	+ Cons: Slower than other approaches due to the additional processing power required for regex parsing.
* **/rexex2 approach:**
	+ Pros: Combines benefits of regular expressions and `replace()` method, potentially offering better performance than individual approaches.
	+ Cons: May still incur additional overhead due to regex parsing.

**Other Alternatives**

Some alternative approaches that are not tested in this benchmark include:

* Using `match()` method with a regular expression
* Using `localeCompare()` method to compare strings
* Using `indexOf()` and slicing the string manually

These alternatives may offer different trade-offs between performance, simplicity, and maintainability.