Benchmark: Check first character

Script Preparation code:

var value = "Fourscore and seven years"

Tests:

regexp .test()
/^F.*/.test(value)
String match
value.matches(/^F.*/)
Start startsWith
value.startsWith('F')
String charAt
value[0]==='F'
String indexOf
value.indexOf('F')===0

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regexp .test()
String match
Start startsWith
String charAt
String indexOf

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 the provided JSON data and explain what's being tested.

**Benchmark Definition**

The benchmark is designed to measure the performance of different methods for checking if the first character of a string matches a certain pattern or value. The script preparation code sets up a string variable `value` with the text "Fourscore and seven years".

**Options Compared**

The benchmark compares five different approaches:

1. **Regular Expression (.test())**: This method uses the `.test()` function from JavaScript's String prototype to check if the first character of the string matches the pattern.
2. **String.match()**: This method uses the `match()` function from JavaScript's String prototype to search for a regular expression pattern in the string and returns an array containing any full match of that pattern, or null if no match is found. The benchmark specifically checks if the first character of the string matches the pattern.
3. **StartsWith()**: This method uses the `startsWith()` function from JavaScript's String prototype to check if the string starts with a specified value (in this case, "F").
4. **charAt()**: This method uses the `[0]` indexing syntax to access the first character of the string and then compares it with the pattern using the `===` operator.
5. **indexOf()**: This method uses the `indexOf()` function from JavaScript's String prototype to search for a specified value (in this case, "F") in the string and returns its position if found.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **Regular Expression (.test())**:
	* Pros: Efficient and flexible way to match patterns.
	* Cons: Can be slower for simple cases due to the overhead of creating a regex object.
2. **String.match()**:
	* Pros: Can handle more complex pattern matching, including capturing groups.
	* Cons: Returns an array or null, so additional processing is required to extract the first character.
3. **StartsWith()**:
	* Pros: Simple and efficient for simple cases.
	* Cons: Limited flexibility; only checks if the string starts with a specific value.
4. **charAt()**:
	* Pros: Fast and simple for simple cases.
	* Cons: Requires indexing into the string, which can be slower than other methods.
5. **indexOf()**:
	* Pros: Efficient and flexible way to find the first occurrence of a value in the string.
	* Cons: Returns an index, not a boolean result.

**Other Considerations**

* The benchmark uses Chrome 101 as the user agent string, which means the results may not be representative of other browsers or environments.
* The device platform is set to Desktop, which might affect the performance results compared to mobile devices.

**Library and Purpose**

In this benchmark, there are no external libraries being used beyond JavaScript's built-in String prototype methods.

**Special JS Features or Syntax**

There are a few special features or syntax elements in this benchmark:

* The `/^F.*/` regular expression pattern uses:
	+ `^` to match the start of the string
	+ `F` to match the character "F" literally
	+ `.*` to match any characters (including none) after the first "F"
* The `.test()` function is used with a regular expression, which is a special syntax for matching patterns in JavaScript.

**Alternatives**

If you're looking for alternatives to this benchmark or want to explore other approaches, here are some options:

1. Use a different string value or pattern to change the focus of the benchmark.
2. Add more test cases to cover edge cases, such as empty strings or null inputs.
3. Compare performance with other programming languages, like Python or C++.
4. Experiment with different regex flavors (e.g., PCRE) or use external libraries for regular expression matching.

By understanding these options and considerations, you can better appreciate the nuances of the benchmark and make informed decisions about how to optimize your own string manipulation code.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.54 Safari/537.36

Browser/OS: Chrome 101 on Windows

View result in a separate tab

Test name	Executions per second
regexp .test()	4185211.5 Ops/sec
String match	0.0 Ops/sec
Start startsWith	6917659.0 Ops/sec
String charAt	6991076.5 Ops/sec
String indexOf	7259267.0 Ops/sec

Related benchmarks:

Check first character (version: 0)

Comparing performance of: regexp .test() vs String match vs Start startsWith vs String charAt vs String indexOf

Created: 2 years ago by: Guest

Jump to the latest result

regexp .test()

String match

Start startsWith

String charAt

String indexOf

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):