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

Benchmark Overview

The benchmark consists of three test cases: eval, new Function, and regular. The goal is to compare their performance in executing a specific JavaScript function. We'll break down each test case, explain what's happening under the hood, and discuss pros and cons.

Test Case 1: eval

eval is a built-in JavaScript function that executes a string as if it were code. In this test case, the string "let r = Math.random().toString(36).substring(7).includes('x');;" defines a variable r using a random value generated by Math.random(). The eval function then evaluates and returns the result of that expression.

Pros:

• Simple to implement
• Fast execution (since it's just interpreting code)

Cons:

• Potential security risks, as eval can execute arbitrary code
• May be slower due to the overhead of parsing and executing the string

Test Case 2: new Function

In this test case, a new function is created using the new Function syntax. The same string "let r = Math.random().toString(36).substring(7).includes('x');;" defines a variable r, just like in the eval test case.

Pros:

• Similar to eval, but with better security guarantees
• May be faster due to the compiler optimization of the generated code

Cons:

• Still involves function creation, which can incur overhead
• Not as simple to implement as eval

Test Case 3: regular

This test case uses a named function expression instead of new Function or eval. The same string "let r = Math.random().toString(36).substring(7).includes('x');;" defines a variable r, just like in the other two test cases.

Pros:

• Similar to eval and new Function
• May be faster due to the compiler optimization of the generated code

Library/Function Usage

None of these test cases use any external libraries or functions. The focus is on comparing the performance of different JavaScript features.

Special JS Features/Syntax

There are no special JavaScript features or syntax used in this benchmark. It's a straightforward comparison of three simple execution methods.

Alternative Approaches

Other approaches to executing code could include:

• String.prototype.execute() (if supported by the browser)
• Function(), without using new
• Compiler-based optimizations, such as ES6 modules or WebAssembly
• Native code generation and execution (e.g., using WebAssembly)

Keep in mind that these alternatives might not be supported by all browsers or environments. MeasureThat.net's focus is on comparing JavaScript features, so it uses a more controlled and standardized approach.

I hope this explanation helps you understand what's happening in the MeasureThat.net benchmark!