Benchmark: Double a number - MeasureThat.net

Script Preparation code:

let a = 10;

Tests:

BitShift
let a = 10; a << 1;
Times Equals
let a = 10; a *= 2

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
BitShift
Times Equals

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.4 Safari/605.1.15

Browser/OS: Safari 18 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
BitShift	475681888.0 Ops/sec
Times Equals	492127392.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark, "Double a number", is a simple JavaScript microbenchmark that tests two different approaches to doubling a number: using bit shifting (`a << 1`) or multiplication (`a *= 2`).

**Test Case Options Compared**

There are two test cases:

1. **BitShift**: This test case uses the bit shifting operator (`<<`) to double the value of `a`.
2. **Times Equals**: This test case uses the multiplication assignment operator (`*=`) to double the value of `a`.

**Pros and Cons of Each Approach**

*   **BitShift**:
    *   Pros:
        *   Can be more efficient in terms of CPU cycles, as it only requires a single bit shift operation.
        *   Often faster than multiplication due to the CPU's ability to perform bitwise operations more quickly.
    *   Cons:
        *   May not work correctly on all data types (e.g., floating-point numbers).
        *   Requires two operands: the number to be doubled and the result.
*   **Times Equals**:
    *   Pros:
        *   More readable and intuitive for most developers.
        *   Works with any numeric type, including floating-point numbers.
    *   Cons:
        *   Often slower than bit shifting due to the CPU's overhead in executing multiplication.

**Other Considerations**

*   **Library Usage**: None of the test cases uses a JavaScript library. If a library were used, it would likely impact the performance comparison between these two approaches.
*   **Special JS Features or Syntax**: Neither of the test cases utilizes any special JavaScript features or syntax beyond basic arithmetic operations.

**Alternatives**

If you wanted to create alternative benchmarking test cases for this same "Double a number" scenario, some potential options could include:

*   **Using different data types** (e.g., `a = 10.5` instead of `let a = 10;`)
*   **Adding more variables or side effects** (e.g., `a = 10; let b = 0; b += a * 2`)
*   **Comparing different JavaScript engines or versions**
*   **Measuring the memory allocation requirements for each approach**

Keep in mind that the specific alternatives you choose will depend on your testing goals and requirements.

I hope this explanation helps provide clarity to anyone looking at these benchmark tests.

Related benchmarks:

Double a number (version: 0)

Double a number by bitshift or just doubling

Comparing performance of: BitShift vs Times Equals

Created: 7 years ago by: Guest

Jump to the latest result

BitShift

Times Equals

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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