Benchmark: Decoding ascii: TextDecoder vs Js

Script Preparation code:

// needed to create bytes array
var encoder = new TextEncoder();
// string length, multiple of 4 - vary to get different results
var n = 8;
var arr = encoder.encode(Array((n / 4) | 0).fill('abcd'));
var decoder = new TextDecoder();
function decodeNative(arr) {
  return decoder.decode(arr);
}

function decoderJs(buffer) {
  var start = 0;
  var end = buffer.byteLength;

  if (end - start < 1) {
    return "";
  }

  var str = "";
  for (var i = start; i < end;) {
    var t = buffer[i++];

    if (t <= 0x7F) {
      str += String.fromCharCode(t);
    } else if (t >= 0xC0 && t < 0xE0) {
      str += String.fromCharCode((t & 0x1F) << 6 | buffer[i++] & 0x3F);
    } else if (t >= 0xE0 && t < 0xF0) {
      str += String.fromCharCode((t & 0xF) << 12 | (buffer[i++] & 0x3F) << 6 | buffer[i++] & 0x3F);
    } else if (t >= 0xF0) {
      var t2 = ((t & 7) << 18 | (buffer[i++] & 0x3F) << 12 | (buffer[i++] & 0x3F) << 6 | buffer[i++] & 0x3F) - 0x10000;
      str += String.fromCharCode(0xD800 + (t2 >> 10));
      str += String.fromCharCode(0xDC00 + (t2 & 0x3FF));
    }
  }
  return str;
}

Tests:

decodeNative
decodeNative(arr)
decoderJs
decoderJs(arr)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
decodeNative
decoderJs

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested in the provided JSON benchmark.

**Benchmark Definition**

The main goal of this benchmark is to compare the performance of two different approaches for decoding ASCII text using JavaScript:

1. `decodeNative(arr)`: This function uses the built-in `TextDecoder` API, which is a part of the Web API.
2. `decoderJs(buffer)`: This function implements manual decoding logic for UTF-8 encoded strings.

**Options Compared**

The benchmark compares the performance of these two approaches with varying string lengths. The tests are designed to measure the execution time (in executions per second) for each approach as the input string length increases.

**Pros and Cons**

1. **TextDecoder API (`decodeNative(arr)`)**:
	* Pros: Built-in, widely supported, and optimized for performance.
	* Cons: Requires a browser to support the Web API, and might not be available in older browsers or environments with limited JavaScript capabilities.
2. **Manual decoding logic (`decoderJs(buffer)`)**:
	* Pros: Can be implemented on any platform that supports JavaScript, including Node.js and other environments where `TextDecoder` is not available.
	* Cons: Requires more code and effort to implement correctly, and might be slower due to the overhead of manual decoding logic.

**Other Considerations**

When using the `TextDecoder` API, it's essential to note that:

* The browser must support the Web API for this benchmark.
* The input string should be a valid UTF-8 encoded string.

For the manual decoding logic (`decoderJs(buffer)`), make sure to handle edge cases and encoding errors correctly.

**Library: `TextEncoder`**

The `TextEncoder` library is used to create a buffer from a string, which is then passed as an argument to the `decodeNative(arr)` function. This buffer is expected to contain the encoded data in UTF-8 format.

**JavaScript Features/Syntax**

This benchmark does not use any special JavaScript features or syntax that are specific to certain browsers or environments. However, it relies on modern JavaScript features like `const`, `let`, and arrow functions, which might not be supported in older browsers or environments with limited JavaScript capabilities.

In summary, this benchmark tests the performance of two approaches for decoding ASCII text: using the built-in `TextDecoder` API versus implementing manual decoding logic. The results provide insight into the execution time of each approach under various conditions, helping developers optimize their code for better performance.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:99.0) Gecko/20100101 Firefox/99.0

Browser/OS: Firefox 99 on Linux

View result in a separate tab

Test name	Executions per second
decodeNative	6869118.5 Ops/sec
decoderJs	4343495.5 Ops/sec

Related benchmarks:

Decoding ascii: TextDecoder vs Js (version: 0)

Measure performance of ascii decoding for various string lengths.

Comparing performance of: decodeNative vs decoderJs

Created: 2 years ago by: Registered User

Jump to the latest result

decodeNative

decoderJs

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):