Benchmark: Regex vs .indexOf vs .startsWith vs .substr sdfg sdf gsd

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; }
.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
.startsWith

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

**Overview**

The provided JSON represents a JavaScript microbenchmark test case for measuring the performance of different string comparison methods: regular expressions (`regex`), `indexOf`, and `startsWith`. The test case creates an array of random strings, iterates over them, and applies each comparison method to verify if a specific pattern exists in the string.

**Benchmarked Options**

The three options being compared are:

1. **Regular Expressions (`regex`)**: A pattern-based search that allows for regular expression patterns to be used for matching.
2. **`indexOf`**: A method that returns the index of the first occurrence of a substring within another string.
3. **`startsWith`**: A method that returns a boolean indicating whether a string starts with another string.

**Pros and Cons**

* **Regular Expressions (`regex`)**:
	+ Pros: flexible, powerful, and supports complex patterns.
	+ Cons: slow performance due to the overhead of compiling and executing regular expression patterns.
* `indexOf`:
	+ Pros: simple, fast, and widely supported.
	+ Cons: may not work correctly for edge cases (e.g., empty strings) or Unicode characters.
* `startsWith`:
	+ Pros: fast, efficient, and suitable for most use cases.
	+ Cons: limited to checking if a string starts with another; does not support substring searches.

**Libraries and Special JS Features**

The test case uses the following library:

* None explicitly mentioned, but it assumes that the `window` object is available, which suggests using a browser or Node.js environment.

There are no special JavaScript features used in this benchmark. However, note that the use of `RegExp` (regular expression) would be denoted by the `R` symbol, not shown here.

**Other Alternatives**

For string comparison methods, other alternatives to consider:

* `includes`: A method introduced in ECMAScript 2015 (ES6+) that returns a boolean indicating whether a string includes another substring.
* `contains`: Not a standard JavaScript method; consider using `includes` instead.

Keep in mind that these alternatives may have different performance characteristics and use cases compared to the options being benchmarked.

Related benchmarks:

Regex vs .indexOf vs .startsWith vs .substr sdfg sdf gsd (version: 0)

Testing some things

Comparing performance of: Regex vs .indexOf vs .startsWith

Created: 6 years ago by: Guest

Jump to the latest result

Regex

.indexOf

.startsWith

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):