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: 7 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

Test name	Executions per second
startsWith	1179.1 Ops/sec
split	95.6 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.

Related benchmarks:

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: 2 years ago by: Guest

Jump 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):