Benchmark: startsWith or regex test

Script Preparation code:

window.myString = "Hello, world!";
window.prefix = "Hello";
window.regex = /^Hello/;

Tests:

startsWith
if (myString.startsWith(prefix)) { // do something }
regex
if (regex.test(myString)) { // do something }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startsWith
regex

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36

Browser/OS: Chrome 119 on Linux

View result in a separate tab

Test name	Executions per second
startsWith	6394741.5 Ops/sec
regex	6338390.0 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 benchmark definition and test cases to understand what is being tested.

**Benchmark Definition**

The provided JSON defines a benchmark named "startsWith or regex test". The description is null, which means there isn't any additional context about the benchmark. However, the script preparation code sets up two variables:

* `window.myString`: a string literal with the value `"Hello, world!"`.
* `window.prefix`: another string literal with the value `"Hello"`.
* `window.regex`: a regular expression object with the value `/^Hello/`.

The purpose of these variables is to create a test scenario where two different approaches are compared:

1. **startsWith**: This approach checks if the `myString` starts with the `prefix` using the `startsWith()` method.
2. **regex**: This approach uses a regular expression to match the `myString` against the `/^Hello/` pattern.

**Options being compared**

The two options being compared are:

1. **Regular string comparison (`startsWith()`)**: This is a simple and efficient way to check if one string starts with another.
2. **Regular expression matching**: This approach uses a regular expression to match the `myString` against a specific pattern. Regular expressions can be powerful tools for pattern-matching, but they can also be slower than simple string comparisons.

**Pros and Cons of each approach**

**startsWith()**

Pros:

* Fast: String comparison is generally fast.
* Efficient: This approach doesn't require creating a regular expression object or compiling the regex pattern.

Cons:

* May not work as expected for non-ASCII characters or Unicode characters that don't start with the prefix.
* May be slower than using regular expressions if the prefix is longer than the `myString`.

**Regular Expression Matching**

Pros:

* Flexible: Regular expressions can match a wide range of patterns, including non-string data types like numbers and dates.
* Powerful: Regular expressions can perform complex pattern-matching, such as matching strings within strings or extracting specific parts of a string.

Cons:

* Slower: Creating and compiling regular expression objects can be slower than simple string comparisons.
* Less readable: Complex regular expression patterns can be difficult to read and understand.

**Library used**

In this benchmark, the `regex` option uses the built-in JavaScript `test()` method, which is a part of the ECMAScript standard. The `test()` method takes two arguments: the string to test against the regex pattern, and the regex pattern itself.

**Special JS feature or syntax**

None are mentioned in this benchmark definition.

Now, let's look at the individual test cases:

1. **Test Case 1: "startsWith"**
This test case runs the `if (myString.startsWith(prefix))` code multiple times to measure its performance.
2. **Test Case 2: "regex"**
This test case runs the `if (regex.test(myString))` code multiple times to measure its performance.

**Alternative approaches**

If you want to use a different approach, here are some alternatives:

* Use a different string comparison method, such as using the `localeCompare()` method or the `indexOf()` method.
* Use a more complex regular expression pattern, such as one that uses character classes or anchors.
* Use a different library or framework for regular expression matching, such as jQuery's `regex` function.

Note that these alternative approaches may have different performance characteristics and trade-offs compared to the original benchmark.

Related benchmarks:

startsWith or regex test (version: 0)

Comparing performance of: startsWith vs regex

Created: 2 years ago by: Guest

Jump to the latest result

startsWith

regex

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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