Benchmark: floor vs bitwise-not

Script Preparation code:

window.array = [...Array(1000)].map((x, idx) => idx)

Tests:

floor
const rnd = window.array[Math.floor(Math.random() * window.array.length)]
bitwise-not
const rnd = window.array[~~(Math.random() * window.array.length)]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
floor
bitwise-not

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 using the `Math.floor()` function and the bitwise NOT operator (`~`) to select an element from an array. The script generates an array of 1000 elements, each representing a random index.

**Script Preparation Code**

The "Script Preparation Code" section is crucial in setting up the benchmark:
```javascript
window.array = [...Array(1000)].map((x, idx) => idx);
```
This code creates a window object `array` with an array of 1000 elements, where each element is a random index between 0 and 999. This array will be used to select the random element for testing.

**Html Preparation Code**

The "Html Preparation Code" section is empty, which means no HTML preparation is required for this benchmark.

**Test Cases**

There are two test cases:

1. `floor`: uses `Math.floor()`
```javascript
const rnd = window.array[Math.floor(Math.random() * window.array.length)];
```
2. `bitwise-not`: uses the bitwise NOT operator (`~`) to select an element:
```javascript
const rnd = window.array[~~(Math.random() * window.array.length)];
```
**Pros and Cons**

Using `Math.floor()`:

* Pros: more readable and maintainable code, handles edge cases like negative numbers and floating-point values.
* Cons: slower for large arrays due to the overhead of the `Math.floor()` function.

Using bitwise NOT (`~`):

* Pros: faster performance, especially for large arrays, since it's a simple bitwise operation.
* Cons: less readable and maintainable code, may not work correctly for edge cases like negative numbers or floating-point values.

**Library**

There is no explicit library mentioned in the benchmark. However, the `window.array` variable is created using the spread operator (`...`) and an array comprehension, which are built-in JavaScript features.

**Special JS Feature/Syntax**

The bitwise NOT operator (`~`) is a special feature in JavaScript that performs a bitwise negation on its operand. It's not as commonly used as other operators, but it can be useful in certain situations.

**Other Alternatives**

If you need to select an element from an array without using `Math.floor()` or the bitwise NOT operator, you could use other approaches:

* Use the `at` method (ES2019+): `const rnd = window.array.at(Math.random() * window.array.length);`
* Use a simple loop: `let index = Math.floor(Math.random() * window.array.length); const rnd = window.array[index];`

Keep in mind that these alternatives may have different performance characteristics or readability trade-offs compared to the original benchmark.

Related benchmarks:

floor vs bitwise-not (version: 0)

Comparing performance of: floor vs bitwise-not

Created: 5 years ago by: Guest

Jump to the latest result

floor

bitwise-not

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):