Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

Benchmark Definition The benchmark is defined by providing a Script Preparation Code and an optional Html Preparation Code. However, in this case, both fields are empty, indicating that the script preparation code will be generated automatically by the browser. The benchmark definition also specifies two test cases: "builtin plus operator" and "custom sum method".

Test Cases The test cases compare the performance of two approaches to calculate the sum of an array:

1. Builtin Plus Operator: This test case uses the built-in + operator to add all numbers in the array.
2. Custom Sum Method: This test case defines a custom JavaScript function, getSum, which uses the reduce() method to add all numbers in the array.

Options Compared The benchmark compares the performance of these two approaches:

• Builtin Plus Operator: Uses the built-in + operator to add all numbers in the array.
• Custom Sum Method: Defines a custom JavaScript function, getSum, which uses the reduce() method to add all numbers in the array.

Pros and Cons

• Builtin Plus Operator:
  • Pros:
    • Fast execution
    • Simple implementation
  • Cons:
    • Limited control over iteration order
    • May be optimized by browsers
• Custom Sum Method:
  • Pros:
    • Control over iteration order
    • More flexible implementation
  • Cons:
    • Slower execution (due to function call overhead)
    • More complex implementation

Library and Syntax There is no specific library mentioned in the benchmark definition. However, the custom sum method uses the reduce() method, which is a part of the ECMAScript standard.

Special JS Feature or Syntax The custom sum method uses the function keyword to define a new function, getSum, and the => syntax for arrow functions (introduced in ECMAScript 2015). The reduce() method is also a part of the ECMAScript standard.

Other Alternatives There are other ways to calculate the sum of an array in JavaScript, such as using a for loop or the Array.prototype.reduce() method with a callback function. Some examples include:

• Using a for loop: let sum = 0; for (let i = 0; i < arr.length; i++) { sum += arr[i]; }
• Using Array.prototype.reduce(): arr.reduce((a, b) => a + b, 0)
• Using map() and reduce(): arr.map(x => x).reduce((a, b) => a + b, 0)

Keep in mind that the performance differences between these approaches may vary depending on the specific use case and browser implementation.