Benchmark: Substring vs Bitmask

Tests:

String()
let num = 255; let nums = []; for(let i = 0; i < 100; ++i) { nums.push(num.toString(2).padStart(8, '0').substring(0, 4)); }
.toString()
let num = 255; let nums = []; for(let i = 0; i < 100; ++i) { nums.push((num >> 4) & 0xF); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String()
.toString()

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to extract a specific substring from a binary number represented as a hexadecimal string:

1. Using the `String()` method
2. Using bitwise operations (specifically, shifting and masking)

**Options Compared**

Two options are compared:

a. **`String()`**: This is the traditional way of converting a number to a string in JavaScript. It uses the built-in `toString()` method and formats the result as a hexadecimal string.

b. **Bitwise operations**: This approach uses bitwise shifts (left shift `>> 4`) and masking (`& 0xF`) to extract the desired substring from the binary representation of the number.

**Pros and Cons**

a. **`String()`**:

Pros:

* Easy to understand and implement
* Works well for small numbers

Cons:

* Can be slow for large numbers due to string formatting overhead
* May not be efficient for very large binary strings

b. **Bitwise operations**:

Pros:

* Fast and efficient, especially for large numbers
* Avoids string formatting overhead

Cons:

* Requires understanding of bitwise operations and their implications
* May be more difficult to read and maintain than the traditional approach

**Library and Special JS Features**

Neither of these options uses a specific library. However, it's worth noting that JavaScript engines like SpiderMonkey (used by Firefox) may optimize certain instructions or use special features like SIMD (Single Instruction, Multiple Data) instructions.

**Other Considerations**

When choosing between these approaches, consider the following:

* **Performance**: If you need to process large numbers or binary strings frequently, bitwise operations might be a better choice.
* **Readability and maintainability**: If code readability is more important than performance, the `String()` method might be a better option.

**Alternatives**

Other alternatives for extracting substrings from binary strings in JavaScript include:

1. Using a library like `utf8-js` or `hex-strings` to convert between binary and string representations.
2. Implementing custom bit manipulation functions using bitwise operators.
3. Using a streaming library to process binary data in chunks, which might be more efficient for very large inputs.

Keep in mind that these alternatives may not offer significant performance improvements over the original benchmarked approaches, and might add complexity or dependencies to your codebase.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux aarch64; rv:109.0) Gecko/20100101 Firefox/113.0

Browser/OS: Firefox 113 on Ubuntu

View result in a separate tab

Test name	Executions per second
String()	727744.4 Ops/sec
.toString()	2994715.0 Ops/sec

Related benchmarks:

Substring vs Bitmask (version: 0)

Comparing performance of: String() vs .toString()

Created: 2 years ago by: Guest

Jump to the latest result

String()

.toString()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):