Benchmark: char index vs charAt()

Script Preparation code:

var str = '!foo bar baz';
var noop = Function.prototype;

Tests:

character index
if (str[0] === '!') noop();
charAt()
if (str.charAt(0) === '!') noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
character index
charAt()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36

Browser/OS: Chrome 81 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
character index	5092041.5 Ops/sec
charAt()	5075358.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is essential to identify optimization opportunities and ensure the best user experience.

The provided benchmark, "char index vs charAt()", tests two methods for accessing the first character of a string: using bracket notation (`str[0]`) and the `charAt()` method. Let's break down what's being tested and compare these approaches:

**Methods being compared:**

1. **Bracket notation (`str[0]`)**: This method accesses the first element of an array-like object (in this case, a string) using square brackets. It's a simple and widely supported method.
2. **`charAt()` method**: The `charAt()` method returns the character at a specified index in a string. In this test, it's used to access the first character (`0`) of the string.

**Options being compared:**

* Bracket notation
* `charAt()` method

**Pros and Cons:**

* **Bracket notation (`str[0]`)**:
	+ Pros:
		- Wide compatibility across browsers.
		- Fast execution, as it's a direct array access.
	+ Cons:
		- May not be immediately clear to all developers, especially those new to JavaScript.
		- Can lead to confusing code if used incorrectly (e.g., accessing an object by index).
* `charAt()` method:
	+ Pros:
		- More explicit and readable than bracket notation for accessing a character at a specific position.
		- Better suited for iterating over characters in a string using `forEach()`.
	+ Cons:
		- May be slower due to the overhead of calling a method, although this is often negligible.

**Library used:**

In the provided benchmark code, the `noop()` function is defined on the `Function.prototype`. The `noop()` function does nothing and is often used as a placeholder or a way to disable certain features. In this context, it's likely used to prevent optimization of the string index checks by browsers.

**Special JavaScript feature or syntax:**

None mentioned in the provided code.

Now, let's analyze the benchmark results:

The latest benchmark result shows that the bracket notation (`str[0]`) outperforms the `charAt()` method. However, it's essential to consider other factors that might affect performance, such as:

* Browser versions and their optimization techniques.
* String size and complexity (e.g., longer strings may benefit from `charAt()` due to its ability to return a single character).
* Optimizations implemented by browsers for string access.

If you're interested in exploring alternative approaches or optimizing your JavaScript code, consider the following:

* Use the `Intl` API for Unicode-aware string processing.
* Utilize modern JavaScript features like template literals, which can provide better performance and readability.
* Leverage browser-specific optimizations, such as WebAssembly (WASM) or Web Workers.

When measuring JavaScript performance, it's essential to:

1. Test a representative set of use cases.
2. Use multiple browsers and versions.
3. Consider the specific requirements of your application.
4. Optimize for readability, maintainability, and performance.

Remember that optimizing code is an iterative process; gathering data through benchmarks like this one can help inform future optimizations.

Related benchmarks:

char index vs charAt() (version: 0)

Compare methods for testing string's beggining character.

Comparing performance of: character index vs charAt()

Created: 4 years ago by: Guest

Jump to the latest result

character index

charAt()

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):