Benchmark: charCodeAt vs []

Script Preparation code:

var str = "some string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string heresome string here"

Tests:

charCodeAt(0)
str.charCodeAt(0)
charCodeAt(300)
str.charCodeAt(300)
[0]
str[0]
[10]
str[300]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
charCodeAt(0)
charCodeAt(300)
[0]
[10]

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser/OS: Chrome 137 on Windows

View result in a separate tab

Test name	Executions per second
charCodeAt(0)	157620080.0 Ops/sec
charCodeAt(300)	157864384.0 Ops/sec
[0]	154631984.0 Ops/sec
[10]	145157776.0 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 explanation into sections for clarity.

**What is tested on the provided JSON?**

The benchmark tests the performance of two approaches to access characters in a string: using the `charCodeAt()` method and using array indexing (`[]`).

**Options compared:**

1. **charCodeAt() method**: This method returns an integer representing the Unicode character at the specified index.
2. **Array indexing ([])**: This method allows direct access to elements of an array using square brackets.

**Pros and Cons:**

* `charCodeAt()` method:
	+ Pros:
		- Can be used on any string, not just arrays.
		- More explicit and readable for accessing specific characters.
	+ Cons:
		- May incur additional overhead due to Unicode processing.
* Array indexing ([]):
	+ Pros:
		- Fast and efficient for accessing elements in an array.
	+ Cons:
		- Can only be used on arrays, not all strings.

**Library used:**

The benchmark uses the built-in JavaScript `charCodeAt()` method and array indexing (`[]`).

**Special JS feature or syntax:**

None mentioned. However, it's worth noting that using `charCodeAt()` with a large index can involve Unicode processing, which may affect performance.

**Benchmark preparation code:**

The script creates a string literal containing 101 characters repeated multiple times to ensure that the benchmark covers various cases, including accessing different character indices.

**Other alternatives:**

For this specific use case, other alternatives might include using `String.fromCharCode()` instead of `charCodeAt()`, as it allows for more explicit and readable code. Additionally, if the string is known to be encoded in a specific encoding (e.g., UTF-8), using the corresponding `codePointAt()` method might provide better performance.

It's also worth noting that modern JavaScript engines often have optimized implementations of these methods, which can affect performance. The benchmark may not accurately reflect real-world scenarios, where other factors like memory allocation, garbage collection, and caching would come into play.

Related benchmarks:

charCodeAt vs [] (version: 0)

Comparing performance of: charCodeAt(0) vs charCodeAt(300) vs [0] vs [10]

Created: 6 years ago by: Guest

Jump to the latest result

charCodeAt(0)

charCodeAt(300)

[0]

[10]

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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