Benchmark: toFixed vs toPrecision vs Math.round() vs Math.floorfast

Script Preparation code:

var someFloat = 0.123456789;

Tests:

toFixed(4)
someFloat.toFixed(4);
toPrecision(4).toString()
someFloat.toPrecision(4);
(Math.round(*10000)/10000).toString()
(Math.round(someFloat*10000)/10000);
Math.floor fast
~~(someFloat * 10000) / 10000;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
toFixed(4)
toPrecision(4).toString()
(Math.round(*10000)/10000).toString()
Math.floor fast

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
toFixed(4)	8926744.0 Ops/sec
toPrecision(4).toString()	13439743.0 Ops/sec
(Math.round(*10000)/10000).toString()	138189568.0 Ops/sec
Math.floor fast	163922912.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is comparing four different methods to round or truncate a floating-point number:

1. `toFixed()`
2. `toPrecision()`
3. `Math.round()`
4. A custom implementation using bitwise operations (`~~`)

These methods are used to convert a decimal number to an integer, with varying levels of precision.

**Options Compared**

Here's what each method does:

* `toFixed(4)`: Rounds the number to 4 decimal places.
* `toPrecision(4)`: Returns a string representation of the number with a maximum of 4 significant digits. This includes rounding or truncating the number to achieve this level of precision.
* `Math.round()`: Rounds the number to the nearest integer.
* Custom implementation using bitwise operations (`~~`): Uses a trick to round the number to the nearest integer without using `Math.round()`.

**Pros and Cons**

Here's a brief summary:

* `toFixed(4)`:
	+ Pros: Simple, well-established method. Easy to understand and use.
	+ Cons: May lose precision if the decimal part is greater than 0.5.
* `toPrecision(4)`.toString()`:
	+ Pros: Automatically rounds or truncates to achieve a specific level of precision.
	+ Cons: May be slower than `toFixed(4)` due to string conversion.
* `Math.round()`:
	+ Pros: Fast and accurate for rounding to integers.
	+ Cons: Can lose precision if the number is very large or small.
* Custom implementation using bitwise operations (`~~`):
	+ Pros: Fast and lightweight, but may be less intuitive than other methods.
	+ Cons: May cause unexpected behavior in certain situations.

**Library**

The benchmark uses the `~~` operator, which is a bitwise NOT operator in JavaScript. This operator returns `-1` if the number is negative and 0 otherwise. By multiplying the original number by -10000 and then adding 5000, we effectively round to the nearest integer using bitwise operations. The resulting value is then cast to an integer using `~~`.

**Special JS Feature**

The benchmark uses a feature called "bitwise operators" (e.g., `~~`), which are not typically used in everyday JavaScript development. This suggests that the test may be targeting specific use cases or hardware platforms where bitwise operations have performance advantages.

**Other Alternatives**

Some other methods for rounding floating-point numbers include:

* Using `Number.EPSILON` to determine the smallest positive value that can be added to 1 without exceeding it, and then using this value as a threshold for rounding.
* Using `Math.ceil()` or `Math.floor()` in combination with conditional statements to achieve the desired level of precision.
* Using specialized libraries like `decimal.js` or `big.js` for high-precision arithmetic.

These alternatives may offer better performance, accuracy, or readability, depending on the specific use case and requirements.

Related benchmarks:

toFixed vs toPrecision vs Math.round() vs Math.floorfast (version: 0)

Comparing performance of: toFixed(4) vs toPrecision(4).toString() vs (Math.round(*10000)/10000).toString() vs Math.floor fast

Created: 5 years ago by: Guest

Jump to the latest result

toFixed(4)

toPrecision(4).toString()

(Math.round(*10000)/10000).toString()

Math.floor fast

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):