Benchmark: TextDecoder 'ascii' vs String.fromCharCode

Script Preparation code:

var bytes = [84,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46];
var bufferArray = new Uint16Array(bytes);
var decoder = new TextDecoder('ascii'); // default 'utf-8' or 'utf8'

Tests:

String.fromCharCode
String.fromCharCode.apply(null, bufferArray);
TextDecoder
decoder.decode(bufferArray);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String.fromCharCode
TextDecoder

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser/OS: Firefox 128 on Linux

View result in a separate tab

Test name	Executions per second
String.fromCharCode	1901315.4 Ops/sec
TextDecoder	2946608.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The benchmark measures the performance difference between two approaches:

1. **TextDecoder**: A built-in JavaScript API that allows decoding binary data into a string using a specified encoding (e.g., 'ascii', 'utf-8', or 'utf8').
2. **String.fromCharCode**: A method that converts an array of Unicode code points to a string.

**Script Preparation Code:**

The script prepares the test data by:

* Creating a Uint16Array (`bufferArray`) from a binary byte sequence.
* Creating a new TextDecoder instance with the default encoding ('utf-8' or 'utf8').
* Optionally, it's mentioned that `TextDecoder` uses a different encoding ('ascii'), but this is not explicitly tested.

**Html Preparation Code:**

No HTML preparation code is provided, so we can assume that the benchmark is run in a headless environment or a test harness that doesn't require any additional HTML setup.

**Test Cases:**

The individual test cases are:

1. **String.fromCharCode**: Applies the `String.fromCharCode` method to the `bufferArray` array using the `apply()` method.
2. **TextDecoder**: Uses the TextDecoder instance to decode the `bufferArray` into a string using the `decode()` method.

**Library:**

In this case, the library being used is:

* None explicitly mentioned, but the `Uint16Array` and `TextDecoder` APIs are part of the JavaScript standard library.

**Special JS Feature/Syntax:**

There is no special JavaScript feature or syntax being tested in these test cases. The focus is on measuring the performance difference between two established methods for decoding binary data into strings.

**Pros and Cons:**

Here's a brief analysis of the pros and cons of each approach:

* **TextDecoder**:
	+ Pros:
		- More efficient and optimized for decoding binary data into strings.
		- Handles encoding conversions internally, reducing overhead.
	+ Cons:
		- May require more memory allocation due to internal buffering.
* **String.fromCharCode**:
	+ Pros:
		- Simple and straightforward implementation.
		- Can be faster for small arrays or specific use cases.
	+ Cons:
		- Less efficient and optimized compared to TextDecoder.
		- Requires explicit handling of encoding conversions.

**Other Alternatives:**

Some alternative methods for decoding binary data into strings could include:

* **Intl.TextDecoder**: A more modern, internationalized version of TextDecoder that supports various encodings and features like text normalization.
* **Buffer.toString()**: Some implementations provide a `toString()` method on buffers that can be used to convert the contents to a string. However, this may not be as efficient or optimized as using TextDecoder.

Keep in mind that these alternatives might have different performance characteristics, feature sets, or use cases compared to the methods tested in this benchmark.

Related benchmarks:

TextDecoder 'ascii' vs String.fromCharCode (version: 0)

Comparing performance of: String.fromCharCode vs TextDecoder

Created: 4 years ago by: Guest

Jump to the latest result

String.fromCharCode

TextDecoder

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):