Benchmark: toFixed vs toPrecision vs Math.round()

Script Preparation code:

var someFloat = 0.123456789;

Tests:

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

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()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:144.0) Gecko/20100101 Firefox/144.0

Browser/OS: Firefox 144 on Windows

View result in a separate tab

Test name	Executions per second
toFixed(4)	20338112.0 Ops/sec
toPrecision(4).toString()	19812680.0 Ops/sec
(Math.round(*10000)/10000).toString()	2195602176.0 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 provided benchmark and explain what's being tested, compared options, pros and cons, and other considerations.

**Benchmark Overview**

The benchmark compares three different approaches to round a floating-point number:

1. `toFixed(4)`
2. `toPrecision(4).toString()`
3. `(Math.round(someFloat*10000)/10000).toString()` (which is equivalent to `toFixed(4)`)

These approaches aim to achieve the same result, but with different JavaScript methods.

**Options Compared**

The three options being compared are:

1. **`toFixed(4)`**: This method rounds a number to a fixed number of decimal places specified by the argument in parentheses.
2. **`toPrecision(4).toString()`**: This method converts a number to a string representation with a specified number of significant digits (in this case, 4).
3. **`Math.round(someFloat*10000)/10000`.toString()`**: This method rounds a number by multiplying it by a large factor (10,000), rounding to the nearest integer using `Math.round()`, and then dividing by that same large factor.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **`toFixed(4)`**:
	* Pros: Simple, straightforward, and widely supported.
	* Cons: May not be suitable for all use cases (e.g., scientific notation or very large/small numbers).
2. **`toPrecision(4).toString()`**:
	* Pros: More precise than `toFixed(4)`, especially for smaller numbers.
	* Cons: Less intuitive and may require more overhead due to string conversion.
3. **`Math.round(someFloat*10000)/10000`.toString()`**:
	* Pros: Can be faster and more efficient than the other two options, but may introduce additional rounding errors.
	* Cons: More complex and less readable; requires careful tuning of scaling factors.

**Library and Special JS Features**

There is no library being used in this benchmark. However, it's worth noting that `toFixed()` and `toPrecision()` are built-in JavaScript methods, whereas `Math.round()` is also a built-in method.

The special feature here is the use of significant digits (4) as an argument to `toPrecision()`. This is not a commonly used feature, but it allows for more precise control over the output format. In contrast, `toFixed(4)` and `(Math.round(someFloat*10000)/10000).toString()` rely on default settings or scaling factors.

**Other Considerations**

When choosing an approach to round numbers in JavaScript:

* **Accuracy**: If you need precise control over rounding, consider using `toPrecision()`. For simpler use cases, `toFixed(4)` is often sufficient.
* **Performance**: If speed is a concern, consider using the approach with less overhead (e.g., `(Math.round(someFloat*10000)/10000).toString()`).
* **Readability and maintainability**: Choose an approach that balances performance with ease of understanding and modification.

**Alternatives**

Other alternatives for rounding numbers in JavaScript include:

1. `Number.EPSILON`: This is a small value that represents the difference between 1 and a number close to it (e.g., 0.000001). You can use this value as a tolerance when comparing rounded numbers.
2. `Decimal.js` or similar libraries: These libraries provide precise decimal arithmetic with support for rounding, scaling, and more.
3. Other numerical methods (e.g., binary search, interval arithmetic): Depending on your specific requirements, these alternatives might offer advantages over the standard JavaScript methods.

Related benchmarks:

toFixed vs toPrecision vs Math.round() (version: 1)

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

Created: 7 years ago by: Registered User

Jump to the latest result

toFixed(4)

toPrecision(4).toString()

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

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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