Benchmark: JS startsWith vs split upgraded

HTML Preparation code:

<div></div>

Script Preparation code:

window.regexStart = /^test/;
window.regexEnd = /test$/;
window.match = 'self:';
window.matchLength = window.match.length;
var data = window.data = [];
const possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789:";
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:

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; }
split
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; var length = window.matchLength; while (x < TOTAL_STRINGS) { const str = data[x]; str.split(':')[0] === match; x += 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startsWith
split

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36

Browser/OS: Chrome 141 on Linux

View result in a separate tab

startsWith

1K/s

split

96/s

View exact numbers

Test name	Executions per second
✓ startsWith	1,179 Ops/sec
split	96 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 JavaScript microbenchmark and explain what's being tested.

**Benchmark Overview**

MeasureThat.net is comparing the performance of two string manipulation methods: `startsWith` and `split`. The benchmark uses a dataset of 100,000 randomly generated strings to test both approaches.

**What's Being Tested?**

The benchmark tests whether a given string starts with a specific prefix (`startsWith`) or if the first element of a split string is equal to a target value (`split`). Both tests use the same dataset and target values.

**Options Compared:**

1. `startsWith`: This method checks if a given string starts with a specified prefix.
2. `split`: This method splits a string into an array of substrings using a specified separator (in this case, a colon (:)).

**Pros and Cons of Each Approach:**

1. **`startsWith`:**
	* Pros:
		+ Efficient for exact matches
		+ Can use optimized algorithms like the `String.prototype.startsWith()` method in modern browsers
	* Cons:
		+ May be slower for approximate matches or large datasets due to the need for a prefix match
2. **`split`:**
	* Pros:
		+ Can handle partial matches and larger datasets efficiently, as it only needs to split once
	* Cons:
		+ May have higher overhead due to string splitting and array creation

**Library Usage**

The benchmark uses no external libraries beyond the standard JavaScript `String` prototype methods.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax being used in this benchmark. The code only employs standard JavaScript features like loops, functions, and string manipulation methods.

**Alternative Approaches**

Other alternatives to consider for similar string manipulation tasks might include:

1. **Regular Expressions (regex)**: Can be used for both `startsWith` and `split` operations, offering more flexibility but also potential performance overhead.
2. **String.prototype.includes()**: Similar to `startsWith`, but can handle any character match instead of just a prefix.
3. **Substring extraction methods**: Such as `substr()` or `slice()`, which might offer better performance for specific use cases.

Keep in mind that the choice of approach ultimately depends on the specific requirements and constraints of your project.

JS startsWith vs split upgraded (version: 0)

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

Comparing performance of: `startsWith vs split`

Created: 3 years ago by: Guest

Go to the latest result

startsWith

split

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

JS startsWith vs split upgraded (version: 0)

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

Comparing performance of: startsWith vs split

Created: 3 years ago by: Guest

Go to the latest result

startsWith

split

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `startsWith vs split`