Benchmark: round vs add half and floor

Tests:

round
Math.round(13.37) Math.round(13.67)
floor
Math.floor(13.37 + 0.5) Math.floor(13.67 + 0.5)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
round
floor

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.212 Safari/537.36 Edg/90.0.818.66

Browser/OS: Chrome 90 on Windows

View result in a separate tab

Test name	Executions per second
round	2935041.2 Ops/sec
floor	2804786.8 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for rounding numbers:

1. `Math.round(13.37)\r\nMath.round(13.67)`
2. `Math.floor(13.37 + 0.5)\r\nMath.floor(13.67 + 0.5)`

The benchmark is testing the performance of these two approaches on the web browser, specifically Chrome 90.

**Options compared**

Two options are being compared:

1. **`Math.round()`**: This function rounds a number to the nearest integer.
2. **`Math.floor() + 0.5`**: This approach uses `Math.floor()` to round down to the nearest integer and then adds 0.5, effectively rounding up.

**Pros and Cons of each approach**

* **`Math.round()`**:
	+ Pros: Simple and widely supported.
	+ Cons: Can produce NaN (Not a Number) results for certain inputs (e.g., `-0.5`).
* **`Math.floor() + 0.5`**:
	+ Pros: Produces predictable results, avoiding NaN issues.
	+ Cons: More complex and slower due to the addition step.

In general, `Math.round()` is a good choice when you want simple, fast rounding, but be cautious with inputs that might produce NaN results. The `Math.floor() + 0.5` approach provides more control and predictability but comes at the cost of slightly slower performance.

**Library usage**

There doesn't seem to be any specific library being used in these benchmarks, as both examples rely on built-in JavaScript functions (`Math.round()` and `Math.floor()`).

**Special JS feature or syntax**

The benchmark uses a special syntax, `\r\n`, which is an escape sequence for the newline character. This might not be immediately apparent to all users, but it's not a critical issue.

**Other alternatives**

If you were considering alternative approaches, here are a few options:

* **Bourne shell arithmetic**: You could use the `((a + 0.5) > 0 ? a + 0.5 : a)` syntax, which is similar to `Math.floor() + 0.5`. However, this approach might not be compatible with all JavaScript environments.
* **Third-party libraries**: There are several libraries available that provide rounding functions, such as `lodash.round()` or `moment.js`'s `roundTo()`. These libraries might offer additional features or optimizations, but they would add dependencies to your project.

Keep in mind that these alternatives might not always be suitable for performance-critical code, and it's essential to evaluate their trade-offs before choosing an alternative approach.

Related benchmarks:

round vs add half and floor (version: 0)

Comparing performance of: round vs floor

Created: 3 years ago by: Guest

Jump to the latest result

round

floor

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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