Overview

MeasureThat.net is a platform for creating and running JavaScript microbenchmarks. The provided JSON benchmark definition compares the performance of different methods for copying an array in JavaScript: JSON.stringify, slice, Array.from, spread (also known as destructuring), and structuredClone. Let's dive into each method, their pros and cons, and other considerations.

Methods being compared

1. JSON.stringify
2. slice
3. Array.from
4. Spread (destructuring)
5. structuredClone

Pros and Cons of each approach:

• JSON.stringify: This method serializes the entire array into a JSON string, which can be slow for large arrays.
  • Pros: Works well with nested objects, easy to implement.
  • Cons: Slow performance, consumes more memory.
• slice: Creates a shallow copy of a portion of an array. It's efficient but only creates a new array, not a deep copy.
  • Pros: Fast performance, minimal memory allocation.
  • Cons: Only creates a shallow copy, may not work with nested objects.
• Array.from
  • Pros: Works well with both arrays and sets, allows for mapping and filtering options.
  • Cons: May have performance overhead due to the need to create an iterator.
• Spread (destructuring): Creates a shallow copy of an array by spreading its elements into a new array.
  • Pros: Fast performance, creates a shallow copy like slice.
  • Cons: Only works with arrays, not sets or other data structures.
• structuredClone: Creates a deep copy of a value using the Structured Clone algorithm. This method is designed for cloning complex objects.
  • Pros: Deep copying, supports cloning nested objects and arrays.
  • Cons: May be slower than slice or spread, may not work with all data types.

Libraries used

None are explicitly mentioned in the provided benchmark definition, but structuredClone is a built-in JavaScript function introduced in ECMAScript 2022 (ES12).

Special JS features/syntax

None are explicitly mentioned in the provided benchmark definition.

Other alternatives

• Object.assign(): Creates a shallow copy of an array by assigning its elements to a new object.
  • Pros: Works well with arrays and objects, allows for mapping options.
  • Cons: May have performance overhead due to the need to create a new object.
• Array.prototype.map(): Creates a new array with the results of applying a provided function on every element in this array.
  • Pros: Allows for transformation of data, works well with arrays and sets.
  • Cons: May have performance overhead due to the use of functions.

Benchmarking considerations

• Array size: The benchmark definition doesn't specify an array size. However, the choice of array size can significantly impact performance results. Larger arrays may favor more efficient copying methods like slice or spread.
• Browser and JavaScript engine: Different browsers and JavaScript engines may have varying performance characteristics for each method being compared.
• Execution count: The number of executions per second is reported in the benchmark result, which can be affected by factors such as browser cache, disk I/O, and network latency.

Future benchmarks

In the future, MeasureThat.net could consider adding new methods to the comparison, such as:

• Array.prototype.reduce()
• Array.prototype.forEach()
• Array.prototype.entries()
• Array.prototype.sort()

Additionally, exploring different data structures like sets, maps, or objects of other types might provide more comprehensive results.