Benchmark: Regex vs js - MeasureThat.net

Script Preparation code:

var d = [];
for (let i = 0; i < 100000; i++) {
    d.push('/Content/dist/assets/afs-web-review/');
}

Tests:

regex
d.forEach(e => e.replace(/\/$/, ''));
js
d.forEach(e => { if(e.slice(-1) == "/"){ return e.slice(0,-1)+ ""; } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex
js

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.80 Safari/537.36

Browser/OS: Chrome 86 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
regex	120.1 Ops/sec
js	304.3 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The benchmark in question compares two approaches: using a regular expression (`regex`) and string manipulation with `slice()` and conditional statements (`js`).

**Script Preparation Code**

The script preparation code is identical for both test cases:
```javascript
var d = [];
for (let i = 0; i < 100000; i++) {
    d.push('/Content/dist/assets/afs-web-review/');
}
```
This code creates an array `d` with 100,000 elements, all of which are the string `/Content/dist/assets/afs-web-review/`. This array will be used as input for both test cases.

**Html Preparation Code**

The HTML preparation code is empty (`null`) for both test cases. This means that no HTML is generated to accompany the JavaScript benchmark.

**Test Cases**

There are two individual test cases:

1. **regex**
```javascript
d.forEach(e => e.replace(/\\/$/, ''));
```
This test case uses a regular expression to remove the trailing slash (`/`) from each string in the `d` array. The regular expression `/\\/$/` matches the following pattern:
	* `\` (escape character)
	* `$` (end of the string)

The replacement string is an empty string (`''`), effectively removing the trailing slash.

2. **js**
```javascript
d.forEach(e => {
    if (e.slice(-1) == '/'){
        return e.slice(0,-1) + '';
    }
});
```
This test case uses a more traditional JavaScript approach to remove the trailing slash from each string in the `d` array. Here's what happens:

* `e.slice(-1)` returns the last character of the string (`/`)
	* The comparison `== '/'` checks if the last character is a slash
	* If it is, the expression returns the substring of `e` from index 0 to the second-to-last character (effectively removing the trailing slash) followed by an empty string (`''`)

**Latest Benchmark Result**

The latest benchmark result shows two test runs:

1. **js**: Chrome 86 on a Mac desktop with an execution rate of 304.3110656738281 executions per second
2. **regex**: Chrome 86 on a Mac desktop with an execution rate of 120.07433319091797 executions per second

**Pros and Cons**

Here's a brief analysis of the pros and cons of each approach:

**Regex ( regex )**

Pros:

* More concise and expressive syntax
* Can handle more complex string patterns and replacements

Cons:

* May be slower due to the overhead of regular expression processing
* Less intuitive for developers without experience with regular expressions

**JS ( slice() and conditional statements )**

Pros:

* Faster execution rate, possibly due to less overhead than regular expression processing
* More familiar syntax for many JavaScript developers
* Easier to understand and maintain

Cons:

* More verbose and longer code snippets

**Library Considerations**

Neither test case uses a library. However, the use of `slice()` is an inherent part of the ECMAScript standard.

**Special JS Feature or Syntax**

None of the test cases explicitly use any special JavaScript features or syntax (e.g., async/await, arrow functions).

**Alternatives**

If you're interested in exploring alternative approaches, here are some options:

* Use a different string manipulation library like `String.prototype.replace()` with a callback function
* Experiment with different regular expression patterns and replacement strings
* Try using other string processing techniques, such as using `RegExp.exec()` or `String.prototype.replaceAll()`
* Compare the performance of different JavaScript engines or versions

Related benchmarks:

Regex vs js (version: 0)

Comparing performance of: regex vs js

Created: 4 years ago by: Guest

Jump to the latest result

regex

js

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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