Benchmark: Push to array vs Bitwise Mask

Script Preparation code:

var PUSH_BIT = 4;

Tests:

Push to array
const a = [] a.push("test")
Bitwise Mask
let mask = 0; mask |= PUSH_BIT;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Push to array
Bitwise Mask

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:146.0) Gecko/20100101 Firefox/146.0

Browser/OS: Firefox 146 on Windows

View result in a separate tab

Test name	Executions per second
Push to array	26808818.0 Ops/sec
Bitwise Mask	485837056.0 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 benchmark and explain what's being tested.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark that compares two approaches: pushing an element to an array using the `push()` method, and using bitwise masking with the `|=` operator.

**Script Preparation Code**

The script preparation code defines a constant `PUSH_BIT` as 4. This value will be used in the benchmark tests.

**Html Preparation Code**

There is no HTML preparation code provided, which means that only JavaScript code is being executed for these benchmarks.

**Individual Test Cases**

There are two test cases:

1. **Push to array**: This test case defines an empty array `a` and pushes a string `"test"` onto it using the `push()` method.
2. **Bitwise Mask**: This test case defines a variable `mask` initialized to 0, and then uses the bitwise OR assignment operator (`|=`) with the value of `PUSH_BIT` (4).

**Library**

There is no explicit library mentioned in the benchmark definition or test cases.

**Special JS Feature or Syntax**

The use of the `|=` operator (bitwise OR assignment) might be unfamiliar to some developers. The `|=` operator performs a bitwise OR operation on its left operand and assigns the result back to the same variable. In this case, it's used to set a specific bit in the `mask` variable.

**Pros and Cons of Approaches**

1. **Pushing to array**: This approach is straightforward and easy to understand. However, it may be slower due to the overhead of pushing an element onto an array.
2. **Bitwise Mask**: Using bitwise masking can be faster because it directly sets a specific bit in the `mask` variable without creating an intermediate array or performing any additional operations.

**Other Considerations**

* The `Push_BIT` constant is defined as 4, which likely corresponds to the binary representation of 4 (100). This value is used for setting the fourth bit in the `mask` variable.
* The test cases are designed to compare the performance of these two approaches, but other factors like memory allocation, stack size, or specific hardware features might also impact performance.

**Alternative Approaches**

Other alternatives that might be considered in a benchmarking scenario:

* Using `Array.prototype.push()` with a small array (e.g., `[1, 2, 3]`) instead of an empty array.
* Comparing the performance of using `push()` vs. creating a new array and assigning it to a variable (`let arr = [...]; arr.push("test")`).
* Using different data types or structures (e.g., `Set`, `Map`, or objects) for comparison.

Keep in mind that the specific alternatives will depend on the requirements of the benchmark and the test scenarios being evaluated.

Related benchmarks:

Push to array vs Bitwise Mask (version: 0)

Comparing performance of: Push to array vs Bitwise Mask

Created: 6 years ago by: Guest

Jump to the latest result

Push to array

Bitwise Mask

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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