var x = Math.random() * 100000000;
var y;
y = Math.round(x)
y = x > 0 ? (x + 0.5) >> 0 : (x - 0.5) >> 0;
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
round | |
>> |
Test name | Executions per second |
---|---|
round | 4150675.8 Ops/sec |
>> | 5416826.0 Ops/sec |
I'd be happy to explain the benchmarking test case.
Overview
The provided JSON represents a JavaScript microbenchmark that measures the performance of two different rounding algorithms: Math.round()
and a custom implementation using bitwise shift operators (>>
). The benchmark is designed to test how these algorithms perform on integers.
Tested Options
There are only two options being compared:
Math.round(x)
: This is a built-in JavaScript function that rounds a number to the nearest integer.y = x > 0 ? (x + 0.5) >> 0 : (x - 0.5) >> 0;
: This custom implementation uses bitwise shift operators to round a number to the nearest integer.Pros and Cons of Each Approach
1. Built-in Math.round(x)
:
* Pros:
+ Easy to implement and understand.
+ Optimized for performance by the JavaScript engine.
* Cons:
+ May not be as efficient as a custom implementation, especially for large integers.
2. Custom implementation: * Pros: + Can be optimized for specific use cases or hardware architectures. + May provide better performance than the built-in function for certain inputs. * Cons: + More complex and harder to understand, especially for those without experience with bitwise operations. + Requires manual optimization and tuning.
Additional Considerations
The custom implementation uses a technique called "biasing" to round to the nearest even integer. This is done by adding or subtracting 0.5 to the input, depending on whether the number is positive or negative, and then shifting the result right by one bit. This approach can provide a consistent rounding behavior across different hardware architectures.
Library Usage
There are no libraries used in this benchmark.
Special JS Features/Syntax
The custom implementation uses bitwise shift operators (>>
). The >>
operator shifts the bits of its operand to the right and fills 0 on voids left as a result. This is a low-level operation that can provide performance benefits for certain use cases, but may not be suitable for all situations.
Other Alternatives
If you're interested in exploring alternative rounding algorithms or testing different JavaScript features, here are some options:
mathjs
to test the custom implementation on older browsers.Math.round(x) = Math.trunc(x + 0.5)
).Keep in mind that benchmarking is an art, and there's no one-size-fits-all solution. The choice of algorithm, implementation, and testing strategy depends on your specific use case and goals.