Benchmark: Capitalize first char of a string

HTML Preparation code:


<script src=''></script>

Script Preparation code:

var lower = 'this is an entirely lowercase string';

Tests:

charAt
var upper = lower.charAt(0).toUpperCase() + lower.substr(1);
anon function
const upper = lower.replace(/^\w/, c => c.toUpperCase());
function
var upper = lower.replace(/^\w/, function (chr) { return chr.toUpperCase(); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
charAt
anon function
function

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Overview**

The benchmark measures the performance of three different ways to capitalize the first character of a string in JavaScript:

1. Using `charAt()`
2. Using an anonymous function (anonymously defined function)
3. Using a named function

**Comparison Options**

Each test case compares the performance of one specific approach against another, which can be classified into two main categories:

* **Functionality-based comparison**: Comparing different ways to achieve the same goal (capitalizing the first character of a string). This comparison aims to find out which method is most efficient in terms of execution time.
* **Implementation-based comparison**: Comparing the performance of different JavaScript implementations (e.g., Chrome 69, Safari 537.36) and platforms (e.g., Desktop, Mac OS X 10.14.0).

**Pros and Cons of Each Approach**

Here's a brief overview of each approach:

1. `charAt()`
	* Pros: Simple, widely supported, and easy to read.
	* Cons: May not be optimized for performance in all browsers or platforms.
2. Anonymous function (`c => c.toUpperCase()`)
	* Pros: Can be more efficient than traditional functions due to less overhead.
	* Cons: Less readable, may require additional setup (e.g., defining a variable `c`).
3. Named function (`function (chr) { return chr.toUpperCase(); }`)
	* Pros: More readable and maintainable compared to anonymous functions.
	* Cons: May incur more overhead due to the need for a named function.

**Library Usage**

None of the test cases explicitly uses any libraries or external dependencies, except for the `Math` library is implicitly used in all three approaches.

**Special JavaScript Features or Syntax**

The benchmark does not use any special JavaScript features or syntax that would be unique to certain browsers or platforms. The focus is on comparing the performance of different implementation-specific optimizations and approaches.

**Other Alternatives**

There are other alternatives for capitalizing the first character of a string in JavaScript, such as:

* Using template literals: `const upper = `${lower.charAt(0)}${lower.slice(1)}`;
* Using `String.prototype.toUpperCase()` or `String.prototype toupper()`: `var upper = lower.substring(0, 1).toUpperCase() + lower.substring(1);`
* Using a regex with the `^` character class: `const upper = lower.replace(/^./, m => m[1].toUpperCase());`

These alternatives are not tested in the provided benchmark.

Overall, the benchmark provides valuable insights into the performance characteristics of different JavaScript implementations and approaches for a specific use case. By comparing various methods, users can make informed decisions about which approach to use depending on their specific requirements and constraints.

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36

Browser/OS: Chrome 69 on Mac OS X 10.14.0

View result in a separate tab

Test name	Executions per second
charAt	4278518.0 Ops/sec
anon function	1447381.2 Ops/sec
function	1456173.8 Ops/sec

Related benchmarks:

Capitalize first char of a string (version: 0)

Comparing performance of: charAt vs anon function vs function

Created: 6 years ago by: Guest

Jump to the latest result

charAt

anon function

function

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):