function x(z){var fz = Math.floor(z); return [2<<fz, 1<<fz];}; var test0 = x(21.123456789123);function y(z){return [2<<Math.floor(z), 1<<Math.floor(z)];}; var test1 = y(21.123456789123);--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| w/ var | |
| w/o var |
| Test name | Executions per second |
|---|---|
| w/ var | 4621847.0 Ops/sec |
| w/o var | 2581938.2 Ops/sec |
Overview of the Benchmark
The provided benchmark is designed to measure the performance of JavaScript code in various scenarios. Specifically, it tests the execution speed of two different approaches: using var and not using var (also known as "let" or "const").
What's being tested?
In each test case, a simple function is defined that takes a number z as input, performs some arithmetic operations on it, and returns an array with two values. The arithmetic operation involves shifting the bits of z using the left shift operator (<<). The test cases compare the performance of these functions in different browsers.
Options compared
The benchmark tests two main options:
var: This option uses the old-style variable declaration syntax, where z is declared with var. This means that z is a global variable and can be accessed from anywhere in the code.var (let or const): This option uses the new-style variable declaration syntax, where z is declared with const. This means that z is a constant variable and cannot be reassigned.Pros and Cons of each approach
var:var (let or const):Library usage
There is no explicit library mentioned in the benchmark definition. However, it's possible that some internal libraries or frameworks are used to create the test cases.
Special JS feature/syntax
The benchmark uses a special syntax for testing the const keyword: const fz = Math.floor(z);. This syntax is used to declare a constant variable fz and initialize its value with the result of Math.floor(z). The use of const ensures that the variable fz is not reassigned, which can help prevent unexpected behavior.
Other alternatives
If you're interested in testing other JavaScript features or scenarios, here are some alternative approaches:
Keep in mind that writing effective benchmarks requires careful consideration of factors like hardware and software environment, test case complexity, and statistical significance.
