Benchmark: char index vs charAt() for non-zero index

Script Preparation code:

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

Tests:

character index
if (str[5] === 'b') noop();
charAt()
if (str.charAt(5) === 'b') 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: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:130.0) Gecko/20100101 Firefox/130.0

Browser/OS: Firefox 130 on Windows

View result in a separate tab

Test name	Executions per second
character index	106663160.0 Ops/sec
charAt()	101421720.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the benchmark for you.

**What is being tested?**

The benchmark tests two methods to access the first character of a string: `char` indexing and the `charAt()` method. Specifically, it compares the performance of accessing the 6th index (counting from 0) in a string using both approaches.

**Options compared**

Two options are being compared:

1. **Character indexing (`str[5] === 'b'')**: This approach uses direct array access to access the character at a specific index.
2. **`charAt()` method (`str.charAt(5) === 'b'')**: This approach uses a method of the `String` prototype to access and retrieve a single character.

**Pros and cons**

* **Character indexing (`str[5] === 'b'')**:
	+ Pros: Simple, fast, and widely supported.
	+ Cons: May not be as readable or intuitive for developers who are not familiar with array indexing.
* **`charAt()` method (`str.charAt(5) === 'b'')**:
	+ Pros: More readable, well-documented, and often preferred by developers due to its clarity and expressiveness.
	+ Cons: May be slightly slower due to the overhead of calling a method.

**Library and special JavaScript feature**

There is no library being used in this benchmark. However, it's worth noting that some modern browsers may have implemented additional features or optimizations for strings, such as string literals or `String.prototype.at()` (which was introduced in ECMAScript 2015). These features are not relevant to this specific benchmark.

**Other considerations**

* The use of `noop` is likely used to prevent the browser from optimizing away the comparison due to its side-effect-free nature.
* The benchmark uses a short string (`'!foo bar baz'`) to minimize the overhead of creating and initializing the string object. This may not accurately represent real-world scenarios where strings are typically longer.

**Alternative approaches**

Other alternatives to access the first character of a string include:

1. **`substr()` method**: `str.substr(0, 1) === 'b'`
2. **`slice()` method**: `str.slice(0, 1) === 'b'`

These methods are similar to `charAt()`, but may have slightly different performance characteristics or use cases.

In conclusion, the benchmark is testing the relative performance of two approaches to access the first character of a string: direct array indexing and the `charAt()` method. Both approaches have their pros and cons, and the choice between them depends on the specific use case and personal preference.

Related benchmarks:

char index vs charAt() for non-zero index (version: 0)

Compare methods for testing string's beggining character.

Comparing performance of: character index vs charAt()

Created: 5 years ago by: Guest

Jump to the latest result

character index

charAt()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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