Let's dive into the world of JavaScript microbenchmarks and explore what's being tested on MeasureThat.net.

Benchmark Definition The benchmark definition represents a JavaScript snippet that contains the code to be executed. In this case, there are two test cases: "if" and "snake".

Options Compared In both test cases, the same variables are defined:

• j2p32 is set to 2 raised to the power of 32 (using the Math.pow() function)
• i is initialized to 10,000
• x is initialized to 0
• y is initialized to -12

The difference lies in the condition used to update the value of x inside the while loop:

"if" Test Case

tx = (y >= 0 ? y : j2p32 + y);

In this test case, if y is greater than or equal to 0, the expression (y) is evaluated and assigned to x. Otherwise, the value of j2p32 plus y is assigned to x.

"snake" Test Case

tx = y >>> 0;

In this test case, the bitwise right shift operator (>>>) is used. This operator shifts the bits of its operand to the right by a specified number of positions and fills the resulting voids with zeros. In essence, it's equivalent to Math.floor(y / 2 ** 32) (integer division), but uses a different operator.

Pros and Cons

• "if" Test Case:
  • Pros: more readable code, easier to understand the logic
  • Cons: may be slower due to the conditional statement evaluation
• "snake" Test Case:
  • Pros: potentially faster due to the bitwise right shift operation
  • Cons: less readable code, may require additional knowledge of bitwise operations

Library Usage None of the test cases use any external libraries.

Special JavaScript Feature/Syntax The >>> operator used in the "snake" Test Case is a special bitwise right shift operator. This operator performs an arithmetic shift on its operand, which shifts the bits to the right by 32 positions (assuming a 32-bit integer). However, it's worth noting that this operator is not as commonly used as the >> operator with a specified number of positions.

Alternatives Other alternatives for comparing these two test cases could include:

• Using a loop variable and incrementing it instead of decrementing it
• Comparing the results using arithmetic operations instead of conditionals

Please keep in mind that these alternative approaches would likely change the logic and outcome of the benchmark, rather than providing an equivalent comparison to the "if" and "snake" test cases.