Benchmark: fast floor vs floor js

Script Preparation code:

var mathFloor = Math.floor;
var random = Math.random;
var fastFloor = n => {
    if (n >= 0 && n < 0x80000000) {
      return n | 0;
    }
    if (n > -0x80000000 && n < 0) {
      return (n - 1) | 0;
    }
    return mathFloor(n);
};

Tests:

floor
mathFloor(random()*10);
fast floor
fastFloor(random()*10);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
floor
fast floor

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The benchmark measures the performance difference between two approaches to round down a number: `Math.floor` and a custom implementation called `fastFloor`. The test cases are designed to simulate a scenario where a random value is generated, multiplied by 10, and then rounded down using both methods.

**Library Used: None**

There is no external library used in this benchmark. The `fastFloor` function relies on bitwise operations to achieve the rounding behavior.

**JavaScript Feature/ Syntax: Bitwise Operators**

The `fastFloor` implementation uses bitwise operators (`|`) to perform the rounding. Specifically, it uses the following bitwise operation:

* `n | 0`: This operation performs a bitwise OR operation between `n` and 0, effectively truncating the fractional part of `n`.

**Benchmark Preparation Code Explanation**

The preparation code defines two variables: `mathFloor`, which is set to the built-in `Math.floor` function, and `random`, which is set to the built-in `Math.random` function. The `fastFloor` function is then defined using a conditional statement that checks the range of `n` values to determine whether to use bitwise truncation or the built-in `mathFloor` function.

**Options Compared**

The benchmark compares two options:

1. **Built-in `Math.floor`**: This is the traditional way to round down a number in JavaScript.
2. **Custom `fastFloor` implementation**: This implementation uses bitwise operations to achieve the rounding behavior, potentially offering better performance for certain use cases.

**Pros and Cons of Each Approach**

* **Built-in `Math.floor`**:
	+ Pros: Widely supported, easy to understand, and well-documented.
	+ Cons: May not be optimized for specific use cases or hardware architectures.
* **Custom `fastFloor` implementation**:
	+ Pros: Potentially faster execution due to reduced overhead from built-in functions and better cache locality.
	+ Cons: Requires careful consideration of the rounding logic to ensure accurate results, and may not work correctly for all input values.

**Other Considerations**

When designing a custom rounding function like `fastFloor`, it's essential to consider the following:

* **Rounding mode**: Is the function intended to round towards -∞, +∞, or both? Different rounding modes can affect performance.
* **Input range**: Are there specific input ranges where the function should behave differently?
* **Edge cases**: How will the function handle edge cases like NaN (Not a Number) or Infinity values?

**Alternatives**

Other alternatives for rounding numbers in JavaScript include using third-party libraries like `round` from the `mathjs` library, which provides more advanced rounding functions. Additionally, some browsers and engines have built-in optimization for certain rounding operations, so it's worth checking the documentation for specific implementations.

In conclusion, this benchmark highlights the importance of considering performance-critical code paths in JavaScript development. By understanding the trade-offs between different rounding approaches, developers can make informed decisions about which implementation to use in their applications.

Related benchmarks:

fast floor vs floor js (version: 0)

Comparing performance of: floor vs fast floor

Created: 4 years ago by: Guest

Jump to the latest result

floor

fast floor

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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