var someFloat = 13.123456789;
someFloat.toFixed(0);
Math.round(someFloat);
~~(someFloat);
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
toFixed(0) | |
Math.round() | |
Math.floor fast |
Test name | Executions per second |
---|---|
toFixed(0) | 4452365.5 Ops/sec |
Math.round() | 3961814.5 Ops/sec |
Math.floor fast | 12869178.0 Ops/sec |
Let's dive into the world of JavaScript microbenchmarks!
Benchmark Purpose
The provided JSON represents a benchmark that tests how fast different methods are to convert a floating-point number to an integer or a fixed-point representation with a specified precision.
Tested Options
There are four options being compared:
toFixed(0)
: Rounds the number to the nearest integer, effectively truncating any decimal part.Math.round()
: Uses the "banker's rounding" algorithm to round numbers to the nearest even integer.~~ (someFloat)
: A bitwise trick to convert a floating-point number to an integer by taking the integer part of the number after casting it as an unsigned integer (~~
is a unary operator in JavaScript that performs a bit-wise AND operation with the maximum value for the specified type, effectively truncating any negative bits).Math.floor()
: Returns the largest integer less than or equal to the given number.Pros and Cons of Each Approach
toFixed(0)
: Pros: easy to read and understand, works well for most cases. Cons: can lead to loss of precision if not used carefully, as it rounds numbers to the nearest integer.Math.round()
: Pros: handles odd numbers correctly, which can be important in some scenarios. Cons: can produce non-integer results due to the "banker's rounding" algorithm, making it less predictable than other options.~~ (someFloat)
: Pros: fast and efficient way to truncate decimal parts. Cons: uses bitwise operations, which may not be as readable or maintainable for all developers. Additionally, this approach can lead to integer overflow issues if the input is very large.Math.floor()
: Pros: simple and straightforward way to get the largest integer less than or equal to a number. Cons: can produce slightly slower results compared to other options due to its more complex implementation.Library Usage
There are no external libraries used in this benchmark, as all operations are built-in JavaScript functions.
Special JS Features or Syntax
The ~~
operator is a special case in JavaScript that uses bitwise operations to convert a number to an integer. This trick is not well-documented and may be unfamiliar to some developers, but it's a common pattern used in performance-critical code.
Other Alternatives
If you're looking for alternative methods or even more micro-optimizations, here are a few suggestions:
toFixed(0)
, consider using Number.EPSILON
as the precision value instead of hardcoding 0.Math.round()
, you could use Number.EPSILON
as well to make the rounding more precise.~~ (someFloat)
, if you're concerned about overflow issues, consider using a larger data type or a library function like BigInt
.Math.floor()
, you might want to explore other options like decimal.js
or numeral.js
for more precise control over floating-point arithmetic.Keep in mind that these alternatives may introduce additional complexity or performance overhead, so it's essential to weigh the trade-offs before making changes.