Benchmark: startswith vs indexof??

HTML Preparation code:

<div></div>

Script Preparation code:

window.regexStart = /^test/;
window.regexEnd = /test$/;
window.match = 'test';
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; }
indexOf
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.indexOf(match) === 0; x += 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startsWith
indexOf

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the world of JavaScript microbenchmarks.

The provided JSON represents two benchmark definitions:

1. `startswith vs indexof??`
2. Two individual test cases: `startsWith` and `indexOf`

**Benchmark Definition:** "startswith vs indexof??"

This benchmark definition tests the performance difference between using `startsWith()` and `indexOf()` methods on a large dataset of strings.

Let's break down what's being tested:

* `window.regexStart`: A regular expression used as a prefix to match.
* `window.regexEnd`: Another regular expression used as a suffix to match.
* `window.match`: The string to be matched against the prefixes and suffixes.
* `window.matchLength`: The length of the matched string.
* `window.data`: An array of 100,000 random strings, each with a length between 1 and 20 characters.
* `TOTAL_STRINGS`: The total number of strings in the dataset.

The benchmark is designed to test how efficiently these two methods can search for the prefix or suffix in a large dataset.

**Options being compared:**

* `startsWith()`
* `indexOf()`

**Pros and Cons:**

* **`startsWith()`**:
	+ Pros:
		- More efficient when searching for a prefix because it only scans until the first match.
		- Can be faster for strings with prefixes that start from the beginning (e.g., "hello").
	+ Cons:
		- May not be as efficient for strings with no prefix matches, leading to unnecessary scanning.
* **`indexOf()`**:
	+ Pros:
		- More flexible and can find matches anywhere in the string.
		- Can be faster when there are multiple prefix or suffix matches.
	+ Cons:
		- Less efficient than `startsWith()` for finding a single prefix match.

**Library:** None explicitly mentioned, but regular expressions (`regexStart` and `regexEnd`) are used.

**Special JS feature or syntax:**

* The use of template literals (e.g., `"test"` in the `window.match` assignment) is not specific to this benchmark.
* The use of arrow functions (e.g., `str.startsWith(match)` in both benchmarks) is a modern JavaScript feature introduced in ECMAScript 2015.

**Other alternatives:**

* Other string search methods, such as `includes()`, could be used instead of `startsWith()` and `indexOf()`.
* More advanced regular expression techniques, like negative lookahead or lookbehind assertions, might offer better performance for specific use cases.
* Optimized string processing libraries or modules (e.g., `lodash`) could provide alternative implementations with improved performance.

Keep in mind that the choice of method depends on the specific requirements and constraints of your application.

Related benchmarks:

startswith vs indexof?? (version: 0)

Comparing performance of: startsWith vs indexOf

Created: 4 years ago by: Guest

Jump to the latest result

startsWith

indexOf

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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