Benchmark: string startswith vs regexp test

Script Preparation code:

var string = 'localizedTime:dddadfdsfa';
var localizedTimeTagRegex = /^localizedTime:(.+)$/;

Tests:

string startswith
string.startsWith('localizedTime:');
regexp test
localizedTimeTagRegex.test(string);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
string startswith
regexp test

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.0 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 16 on iOS 16.0

View result in a separate tab

Test name	Executions per second
string startswith	14166981.0 Ops/sec
regexp test	7825240.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark definition is a JSON object that contains metadata about the benchmark, including its name, description, script preparation code, and HTML preparation code. In this case:

* The benchmark is named "string startswith vs regexp test".
* There are no provided descriptions.
* The script preparation code defines two variables: `string` with value `'localizedTime:dddadfdsfa'`, and `localizedTimeTagRegex` with a regular expression `/^localizedTime:(.+)$/`. This regex pattern matches the string starting with "localizedTime:" followed by one or more characters (captured in group 1).
* There is no HTML preparation code.

**Individual Test Cases**

The benchmark consists of two test cases:

1. **string startswith**: The first test case uses the `string.startsWith()` method to check if the `string` variable starts with "localizedTime:". This method returns a boolean value indicating whether the string starts with the specified prefix.
2. **regexp test**: The second test case uses the regular expression `/^localizedTime:(.+)$/` (defined in the script preparation code) to match the string starting with "localizedTime:". The `test()` method of the regex object checks if the entire string matches this pattern.

**Pros and Cons**

* **string.startsWith()**:
	+ Pros: Simple, efficient, and widely supported.
	+ Cons: May be slower than regular expression matching for large strings or complex patterns.
* **Regular Expression Matching** (`localizedTimeTagRegex.test(string)`):
	+ Pros: More flexible and powerful for pattern matching, but may be slower than `string.startsWith()` due to the complexity of the regex engine.
	+ Cons: Requires more effort to define a correct regular expression pattern.

**Other Considerations**

When choosing between these two approaches, consider the following:

* If you need to perform simple string comparison with a fixed prefix, `string.startsWith()` is likely sufficient and efficient.
* If you need to match strings against complex patterns or require precise control over the matching process, regular expression matching might be necessary. However, this can come at the cost of performance.

**Library**

There is no explicit library mentioned in the benchmark definition. The regular expression engine is part of the JavaScript standard library.

**Special JS Feature/Syntax**

None are explicitly mentioned in the provided code or test cases.

Related benchmarks:

string startswith vs regexp test (version: 0)

Comparing performance of: string startswith vs regexp test

Created: 2 years ago by: Guest

Jump to the latest result

string startswith

regexp test

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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