Benchmark: Floats: toFixed vs toPrecision vs Math.round

Script Preparation code:

var someFloat = 0.123456789;

Tests:

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

Historical Performance Data aggregated from 14 community runs

Desktop Results:

Chrome 14 runs

Math.round(*10000)/10000

105.5M/s

parseFloat() + toPrecision(4)

8.5M/s

parseFloat() + toFixed(4)

6.7M/s

Fastest: Math.round(*10000)/10000 (15.8x faster)

View exact numbers

✓ Math.round(*10000)/10000: 105,461,568 ops/sec
• parseFloat() + toPrecision(4): 8,453,128 ops/sec
• parseFloat() + toFixed(4): 6,655,225 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
parseFloat() + toFixed(4)
parseFloat() + toPrecision(4)
Math.round(*10000)/10000

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0

Browser/OS: Firefox 140 on Linux

View result in a separate tab

Math.round(*10000)/10000

1504.5M/s

parseFloat() + toFixed(4)

11.7M/s

parseFloat() + toPrecision(4)

9.8M/s

View exact numbers

Test name	Executions per second
✓ Math.round(*10000)/10000	1,504,486,144 Ops/sec
parseFloat() + toFixed(4)	11,696,507 Ops/sec
parseFloat() + toPrecision(4)	9,823,646 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 definition and test cases.

**Benchmark Definition:**

The benchmark measures the performance of three different methods for rounding a floating-point number:

1. `toFixed()`
2. `toPrecision()`
3. `Math.round()` with multiplication and division by 10,000 to avoid floating-point precision issues.

**Options Compared:**

* `parseFloat(someFloat.toFixed(4))`: Uses the `toFixed()` method to convert the float to a string with four decimal places, then parses it back to a float using `parseFloat()`.
* `parseFloat(someFloat.toPrecision(4))`: Uses the `toPrecision()` method to convert the float to a string with four decimal places, then parses it back to a float using `parseFloat()`.
* `Math.round(someFloat*10000)/10000`: Multiplies the float by 10,000, rounds it using `Math.round()`, and then divides the result by 10,000.

**Pros and Cons of Each Approach:**

1. **`toFixed()`**: Pros:
	* Simple to implement.
	* Works well for small numbers with a fixed number of decimal places.
Cons:
	* Can lead to loss of precision due to string conversion.
	* May not work correctly for very large or very small numbers.
2. **`toPrecision()`**: Pros:
	* More flexible than `toFixed()`, allowing for arbitrary precision.
Cons:
	* Less intuitive and more complex to use.
	* May be slower due to the extra operation.
3. **`Math.round()` with multiplication and division by 10,000**:
	* Avoids floating-point precision issues.
	* Works well for large numbers.

**Other Considerations:**

* `toFixed()` is often used when working with user input or data that needs to be presented in a fixed format. However, it can lead to loss of precision if the original value has more decimal places than specified.
* `toPrecision()` is useful when working with very large or very small numbers where precision is critical. However, it may be slower due to the extra operation.

**Library:**

There are no external libraries used in this benchmark definition.

**Special JS Features/Syntax:**

None mentioned explicitly. The benchmark only uses standard JavaScript features and syntax.

Now, let's look at the test cases:

The three test cases measure the performance of the three different rounding methods on a single float value `someFloat` with four decimal places. The test cases are designed to exercise each method individually, without considering interactions or combinations between them.

If you're interested in exploring alternative approaches or optimizing these tests, some potential directions include:

* Using native WebAssembly or AssemblyScript for performance-critical code.
* Investigating the use of SIMD (Single Instruction, Multiple Data) instructions for floating-point operations.
* Optimizing the `Math.round()` multiplication and division by 10,000 to reduce precision issues.
* Implementing a custom rounding algorithm with fine-grained control over precision and performance.

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

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

Created: 5 years ago by: Guest

Go to the latest result

parseFloat() + toFixed(4)

parseFloat() + toPrecision(4)

Math.round(*10000)/10000

Historical Performance Data aggregated from 14 community runs

Desktop Results:

Chrome 14 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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

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

Created: 5 years ago by: Guest

Go to the latest result

parseFloat() + toFixed(4)

parseFloat() + toPrecision(4)

Math.round(*10000)/10000

Historical Performance Data aggregated from 14 community runs

Desktop Results:

Chrome 14 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

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