Benchmark: capitalize first letter of string

Script Preparation code:

function cap1(str) {
  return str.replace(/^./,  i => i.toUpperCase());
}
function cap2(str) {
  return str[0].toUpperCase + str.slice(1);
}

Tests:

slice
cap1("the first letter of this string needs to be capitalized.")
regex
cap2("the first letter of this string needs to be capitalized.")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
regex

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36

Browser/OS: Chrome 62 on Mac OS X 10.12.6

View result in a separate tab

Test name	Executions per second
slice	1232320.5 Ops/sec
regex	2075693.2 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its results.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark named "capitalize first letter of string." The benchmark is designed to test two different approaches for capitalizing the first letter of a string: using the `slice()` method (`cap1`) and using regular expressions (`cap2`).

Here's a brief description of each approach:

* **Cap1 (using slice()):** This approach uses the `slice()` method to extract the first character of the string, converts it to uppercase using the `toUpperCase()` method, and then concatenates it with the rest of the string. The logic is straightforward and easy to understand.
* **Cap2 (using regex):** This approach uses a regular expression (`^./`) to match the first character of the string and convert it to uppercase.

**Options compared**

The two approaches are compared in terms of their performance, which is measured by the number of executions per second. The benchmark runs on different browsers and devices, providing a wide range of results.

**Pros and Cons**

Here's a brief analysis of each approach:

* **Cap1 (using slice()):**
	+ Pros: Easy to understand, straightforward logic, no special regex syntax required.
	+ Cons: May be slower than Cap2 due to the overhead of calling `slice()` and concatenating strings.
* **Cap2 (using regex):**
	+ Pros: Can be faster than Cap1 due to the optimized performance of regular expressions in JavaScript engines.
	+ Cons: Requires knowledge of regex syntax, which can make it harder to understand for some developers.

**Library usage**

Neither approach uses any external libraries. The `slice()` method is a built-in method in JavaScript, and the regular expression used in Cap2 is a standard regex pattern.

**Special JS feature or syntax**

The benchmark does not use any special JavaScript features or syntax beyond what's required to implement the two approaches. No ES6+ syntax, no async/await, etc.

**Other alternatives**

If you wanted to test alternative approaches for capitalizing the first letter of a string, some other options could include:

* Using template literals: `cap3(str) { return `${str[0].toUpperCase()}${str.slice(1)}`; }`
* Using a library like Lodash's `startCase()` function
* Using a different approach altogether, such as using the `charAt()` method and modifying the character directly

These alternatives would require additional benchmarking efforts to compare their performance with Cap1 and Cap2.

Related benchmarks:

capitalize first letter of string (version: 0)

Comparing performance of: slice vs regex

Created: 7 years ago by: Guest

Jump to the latest result

slice

regex

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):