Benchmark: parseFloat(toFixed) vs Math.round()

Script Preparation code:

var someFloat = '0.123456789';

Tests:

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
toFixed
Math.round

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:135.0) Gecko/20100101 Firefox/135.0

Browser/OS: Firefox 135 on Windows

View result in a separate tab

Test name	Executions per second
toFixed	8159346.0 Ops/sec
Math.round	1185677056.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the benchmark being tested on MeasureThat.net.

**Benchmark Overview**

The benchmark tests two different approaches for converting a floating-point number to an integer: using `parseFloat` followed by `toFixed`, and using `Math.round`. The input value is set to `'0.123456789'`.

**Options Compared**

Two options are compared:

1. **`parseFloat(parseFloat(someFloat).toFixed(2);`**: This approach uses the `parseFloat` function twice, first to convert the string to a floating-point number, and then again to extract two decimal places using `toFixed`. The resulting integer value is then returned.
2. **`Math.round(someFloat * 100) / 100;`**: This approach multiplies the input float by 100, rounds the result using `Math.round`, and then divides by 100 to get the original integer value.

**Pros and Cons**

**`parseFloat(parseFloat(someFloat).toFixed(2);`**

Pros:

* More precise control over the number of decimal places
* May be more suitable for certain use cases where a specific precision is required

Cons:

* Requires two function calls, which may lead to increased overhead
* The first `parseFloat` call may not be necessary if the input string already represents a float

**`Math.round(someFloat * 100) / 100;`**

Pros:

* Single function call with minimal overhead
* Avoids unnecessary conversions

Cons:

* May lose precision due to the multiplication and division by 100
* Does not provide direct control over decimal places

**Library: None**

Neither option uses any external libraries. Both are built-in JavaScript functions.

**Special JS Feature or Syntax: None**

There is no special JavaScript feature or syntax being tested in this benchmark.

**Other Alternatives**

If you were to implement these tests yourself, some alternative approaches might include:

* Using `Number` instead of `parseFloat` (since `Number` can parse strings that represent floats)
* Implementing a custom rounding algorithm
* Testing other rounding modes, such as half-even or banker's rounding

However, for most use cases, the built-in JavaScript functions used in this benchmark will provide adequate results.

Related benchmarks:

parseFloat(toFixed) vs Math.round() (version: 0)

Comparing performance of: toFixed vs Math.round

Created: 2 years ago by: Guest

Jump to the latest result

toFixed

Math.round

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):