Benchmark: Regex vs .indexOf vs .includes vs .startsWith

HTML Preparation code:

<div></div>

Script Preparation code:

window.regex = /^test/;
window.match = 'test';
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:

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
.indexOf
.includes
.startsWith

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Benchmark Overview**

The benchmark is comparing the performance of four string manipulation methods: `regex.test()`, `.indexOf()`, `.includes()`, and `.startsWith()` on a large dataset of randomly generated strings. The goal is to determine which method is the fastest.

**Test Cases**

Each test case consists of a single line of code that performs the specified string manipulation operation on a random string from the dataset. The operations being compared are:

1. `regex.test()`: Tests if a regular expression matches a given string.
2. `.indexOf()`: Returns the index of the first occurrence of a substring within a string.
3. `.includes()`: Returns true if a string contains a specified value, otherwise false.
4. `.startsWith()`: Returns true if a string starts with a specified value.

**Pros and Cons**

* `regex.test()`:
	+ Pros: Can perform complex pattern matching, flexible, and efficient for most use cases.
	+ Cons: Can be slower than other methods due to the overhead of compiling regular expressions.
* `.indexOf()`, `.includes()`, and `.startsWith()`:
	+ Pros: Fast and simple implementations that are suitable for common string comparisons.
	+ Cons: May not handle edge cases well, such as null or undefined inputs.

**Library**

The `window.regex` variable is set to a regular expression (`/^test/`) which will be used in the first test case. This suggests that the benchmark is testing the performance of regular expressions against other string manipulation methods.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax being used in this benchmark. The code uses standard JavaScript syntax and does not rely on any modern features like async/await, arrow functions, or destructuring.

**Other Alternatives**

If `regex.test()` is not suitable for your use case, you can consider using other string manipulation methods such as:

* Using a different library or implementation, such as `String.prototype.match()` or `String.prototype.search()`.
* Implementing your own regular expression engine.
* Using a different programming language that provides similar functionality.

In the context of this benchmark, the choice of method depends on the specific use case and performance requirements.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Linux; Android 10; RMX1911) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.85 Mobile Safari/537.36

Browser/OS: Chrome Mobile 94 on Android

View result in a separate tab

Test name	Executions per second
Regex	135.2 Ops/sec
.indexOf	264.7 Ops/sec
.includes	71.7 Ops/sec
.startsWith	97.7 Ops/sec

Related benchmarks:

Regex vs .indexOf vs .includes vs .startsWith (version: 0)

Testing some things

Comparing performance of: Regex vs .indexOf vs .includes vs .startsWith

Created: 2 years ago by: Guest

Jump to the latest result

Regex

.indexOf

.includes

.startsWith

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):