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

Script Preparation code:

var someFloat = 0.123456789;

Tests:

toFixed(4) and parse
+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) and parse
toPrecision(4).toString()
(Math.round(*10000)/10000).toString()
Math.floor fast

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark.

**Benchmark Description**

The benchmark measures the performance of four different approaches to round or format floating-point numbers:

1. `toFixed(4)` with subsequent parsing
2. `toPrecision(4).toString()`
3. `(Math.round(someFloat*10000)/10000)`
4. `~~(someFloat * 10000) / 10000` (a trick using bitwise NOT and integer division)

These approaches are compared to determine which one is the fastest.

**Library**

None of these approaches rely on any specific JavaScript libraries beyond what's provided by the browser (e.g., Chrome).

**Special JS Features/Syntax**

While not explicitly mentioned in this benchmark, all tests assume:

* The use of ES6+ syntax (e.g., `let` for variable declarations).
* A recent version of JavaScript that supports the `someFloat` variable and arithmetic operations.

No special features or syntax are highlighted specifically in these tests; they focus on comparing different numerical rounding strategies.

**Options Comparison**

Here's a brief overview of each option, including pros and cons:

1. **`toFixed(4)` with subsequent parsing**: This approach formats the float to 4 decimal places using `toFixed`, then parses it back to a float. Pros: easy to implement; Cons: can be slower due to string manipulation.
2. **`toPrecision(4).toString()`**: This method formats the float to 4 decimal places using `toPrecision`, then converts it to a string using `toString`. Similar pros and cons as the first approach, with an additional step of converting to a string.
3. **`(Math.round(someFloat*10000)/10000)`**: This trick multiplies the float by 10,000, rounds it to the nearest integer, then divides by 10,000, effectively rounding to 4 decimal places. Pros: simple and fast; Cons: may not be intuitive or efficient for all use cases.
4. **`~~(someFloat * 10000) / 10000`**: This trick uses bitwise NOT (`~~`) to truncate the float to an integer ( effectively rounding down), then divides by 10,000 to get the rounded value. Pros: very fast; Cons: may not be suitable for all use cases and can lead to unexpected behavior.

**Benchmark Results**

The provided benchmark results show that:

* `Math.floor fast` is significantly faster than the other approaches.
* `(Math.round(*10000)/10000).toString()` is also relatively fast but slower than `Math.floor fast`.
* `toPrecision(4).toString()` and `toFixed(4) and parse` are slower.

Keep in mind that these results may vary depending on your specific use case, browser, and JavaScript version.

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 116 on Android

View result in a separate tab

Test name	Executions per second
toFixed(4) and parse	372193.5 Ops/sec
toPrecision(4).toString()	587177.9 Ops/sec
(Math.round(*10000)/10000).toString()	641755.1 Ops/sec
Math.floor fast	1949975.0 Ops/sec

Related benchmarks:

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

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

Created: one year ago by: Guest

Jump to the latest result

toFixed(4) and parse

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 26 days ago):