Benchmark: toFixed vs Math.round vs |(bitwise or)

Script Preparation code:

var someFloat = 0.1256;

Tests:

someFloat.toFixed(2);
someFloat.toFixed(2);
Math.round(someFloat * 100) / 100;
Math.round(someFloat * 100) / 100;
((someFloat * 100) | 0 ) / 100;
((someFloat * 100) | 0 ) / 100;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
someFloat.toFixed(2);
Math.round(someFloat * 100) / 100;
((someFloat * 100) \| 0 ) / 100;

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 12; SM-N975F) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 112 on Android

View result in a separate tab

Test name	Executions per second
someFloat.toFixed(2);	4289698.5 Ops/sec
Math.round(someFloat * 100) / 100;	3824472.5 Ops/sec
((someFloat * 100) \| 0 ) / 100;	11622679.0 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 benchmark and explain what is being tested, compared, and their pros and cons.

**Benchmark Overview**

The test compares the performance of three methods to round or format a floating-point number:

1. `toFixed(2)`: Formats a float as a string with the specified number of digits after the decimal point.
2. `Math.round(someFloat * 100) / 100`: Multiplies the float by 100, rounds to the nearest integer using `Math.round`, and then divides by 100 to get the original value back.
3. `(someFloat * 100 | 0) / 100`: Uses bitwise OR (|) with 0 to effectively truncate the float, and then divides by 100.

**Pros and Cons of Each Approach**

1. `toFixed(2)`:
	* Pros: Simple, readable, and widely supported.
	* Cons: May not be the fastest, as it involves string creation and manipulation.
2. `Math.round(someFloat * 100) / 100`:
	* Pros: Fast and straightforward, but may involve more calculations than necessary.
	* Cons: Requires multiplying by 100, which can lead to overflow or precision issues for large floats.
3. `(someFloat * 100 | 0) / 100`:
	* Pros: Fast and efficient, as it only involves a single multiplication and bitwise operation.
	* Cons: May not be as readable or intuitive, especially for developers unfamiliar with bitwise operations.

**Library Used**

In this benchmark, the `Math.round()` function is used from the built-in JavaScript Math library. The purpose of `Math.round()` is to round a number to the nearest integer, which is then divided by 100 to get back to the original value.

**Special JS Feature/Syntax**

None mentioned in the provided code.

**Alternatives**

Some alternative approaches could be:

1. Using `Number.EPSILON` and comparing the difference between two values to determine if they are close enough to round.
2. Implementing a custom rounding algorithm using bit manipulation or other techniques.
3. Using a library like `decimal.js` for precise decimal arithmetic.

However, these alternatives might not provide significant performance benefits over the built-in `Math.round()` function and may require more code and expertise.

**Benchmark Preparation Code**

The script preparation code is:
```javascript
var someFloat = 0.1256;
```
This sets a sample float value for testing.

**Individual Test Cases**

Each test case consists of a single benchmark definition:

1. `someFloat.toFixed(2);`: Formats the float as a string with two decimal places.
2. `Math.round(someFloat * 100) / 100;`: Multiplies, rounds, and divides to get back to the original value.
3. `(someFloat * 100 | 0) / 100;`: Truncates and divides.

The test result is a list of raw UA strings (browser versions), browser names, device platforms, operating systems, executions per second, and test names for each case.

Related benchmarks:

toFixed vs Math.round vs |(bitwise or) (version: 0)

Comparing performance of:

Comparing performance of: someFloat.toFixed(2); vs Math.round(someFloat * 100) / 100; vs ((someFloat * 100) | 0 ) / 100;

Created: one year ago by: Registered User

Jump to the latest result

someFloat.toFixed(2);

Math.round(someFloat * 100) / 100;

((someFloat * 100) | 0 ) / 100;

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):