Benchmark: JS Regex with OR (url) vs .startsWith

HTML Preparation code:

<div></div>

Script Preparation code:

window.regexStart = /^https:\/\/|^http:\/\//;
window.match = 'http';
window.matchLength = window.match.length;
var data = window.data = [];
const possible = "https://google.com";
var TOTAL_STRINGS = window.TOTAL_STRINGS = 100000;

function getRandomInt(max) {
  return Math.floor(Math.random() * max);
}

function makeRandomString(len) {
  var text = "";
  for( var i=0; i < len; i++ ) {
    text += possible.charAt(getRandomInt(possible.length));
  }
  return text;
}

while (data.length < TOTAL_STRINGS) {
  data.push(makeRandomString(getRandomInt(20)));
}

Tests:

regexStart
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var regex = window.regexStart; while (x < TOTAL_STRINGS) { const str = data[x]; regex.test(str); x += 1; }
startsWith
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str.startsWith(match) === 0; x += 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regexStart
startsWith

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36 Edg/142.0.0.0

Browser/OS: Chrome 142 on Windows

View result in a separate tab

Test name	Executions per second
regexStart	367.1 Ops/sec
startsWith	1003.8 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 provided JSON and explain what's being tested in the benchmark.

**Benchmark Definition**

The benchmark compares two approaches for testing whether a string starts with a specific prefix:

1. `regexStart`: This approach uses a regular expression to test if the string matches the prefix.
2. `startsWith`: This approach uses the built-in `startsWith()` method to test if the string starts with the prefix.

**Options Compared**

Both approaches are compared in terms of their execution speed and accuracy on a set of 100,000 random strings.

**Pros and Cons of Each Approach**

1. **regexStart**
	* Pros:
		+ Can be more flexible, as it allows for regular expression patterns.
		+ May perform better on non-standard prefix formats.
	* Cons:
		+ Can be slower due to the overhead of compiling and executing a regular expression.
		+ May have higher accuracy requirements, such as specifying flags or modifiers.
2. **startsWith**
	* Pros:
		+ Typically faster execution speed due to the built-in method's optimization.
		+ More accurate when using the standard `startsWith()` method behavior.
	* Cons:
		+ Less flexible than regular expressions and may not perform well on non-standard prefix formats.

**Library Used**

Neither approach explicitly uses a library, but both rely on browser-specific features:

1. **regexStart**: Uses the browser's built-in regular expression engine to compile and execute the regex pattern.
2. **startsWith**: Utilizes the `startsWith()` method, which is a standard JavaScript method implemented by most browsers.

**Special JS Features or Syntax**

Neither approach uses any special JavaScript features or syntax that would require additional explanation.

**Alternatives**

If you were to recreate this benchmark, consider using other approaches, such as:

1. **Using a third-party library**: Leverage existing libraries like `regex-approximation` or `string-poseidon` for regular expression optimization and performance.
2. **Custom implementation**: Implement the prefix matching logic from scratch using loops and bitwise operations to compare strings.
3. **Other string comparison methods**: Experiment with other string comparison methods, such as `includes()`, `indexOf()`, or `slice()`.

Keep in mind that these alternatives would require significant changes to the benchmark's setup and implementation.

Overall, this benchmark provides a good starting point for exploring the trade-offs between regular expressions and built-in string methods like `startsWith()`.

Related benchmarks:

JS Regex with OR (url) vs .startsWith (version: 1)

fork of https://www.measurethat.net/Benchmarks/Show/975/11/regex-vs-indexof-vs-startswith-vs-substr

Comparing performance of: regexStart vs startsWith

Created: 2 years ago by: Registered User

Jump to the latest result

regexStart

startsWith

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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