The benchmark "Array clone (spread vs slice vs array.from)" evaluates the performance of three different techniques for cloning an array in JavaScript. Below are the methods compared, their pros and cons, and other considerations.

Techniques Compared

1. Spread Operator ([...])

   • Benchmark Definition: const copy = [...array];
   • Description: This technique uses the spread syntax to create a shallow copy of the array. The spread operator expands the elements of the original array into a new array.
   • Pros:
     • Syntax is concise and clear, making it easy to read.
     • Supports array-like structures and works well with other iterable collections.
   • Cons:
     • Can become less efficient with large arrays or deeply nested structures as it performs shallow copies.

2. Array.prototype.slice()

   • Benchmark Definition: const copy = array.slice();
   • Description: The slice() method returns a shallow copy of a portion of an array into a new array object. When called without any arguments, it returns the complete array.
   • Pros:
     • Also creates a shallow copy in a straightforward manner.
     • Familiar to many developers due to its long presence in JavaScript.
   • Cons:
     • Slightly less modern than the spread operator and can be less intuitive for new developers.

3. Array.from()

   • Benchmark Definition: const copy = Array.from(array);
   • Description: Array.from() creates a new array instance from an array-like or iterable object. In this case, it converts the array to a new array.
   • Pros:
     • Allows transformation during the cloning process by accepting a mapping function as a second argument, if needed.
     • Useful when cloning array-like objects or when you want to provide a more functional programming feel.
   • Cons:
     • Slightly more verbose than the other methods.

Benchmark Results

The executed benchmarks provided the following performance results, measured in Executions Per Second:

• Array.from: 3129.21 executions/second
• Slice: 3105.92 executions/second
• Spread: 2920.31 executions/second

Observations

According to the results, Array.from() performed the best, closely followed by slice(). The spread operator was the slowest in this set of benchmarks. This could be due to how the JavaScript engine optimizes for these operations; certain implementations may be able to better optimize for the built-in Array.from() and slice() compared to the syntactic spread operator.

Other Considerations

• Performance: In cases where performance is critical and you're cloning large arrays, the differences in execution speed might affect the choice of method. The benchmarks showed a notable difference among the three methods, so choosing the fastest method for the specific context is essential.
• Readability and Maintainability: While performance is a consideration, the choice of method should also factor in code readability. The spread operator often offers a cleaner syntax that can enhance maintainability.
• Use Case: Consider whether you need a shallow or deep copy. None of these methods create deep copies, so for objects nested within arrays, a deep copy method (like using JSON.parse(JSON.stringify(array)) or external libraries) should be considered.

Alternatives

• JSON Method: const copy = JSON.parse(JSON.stringify(array)); creates a deep copy but comes with serialization limitations (e.g., does not handle functions, prototypes, or special objects like Date).
• Lodash Library: The Lodash library offers deep cloning methods, such as _.cloneDeep(value), which can be beneficial when working with complex nested structures.

In summary, the benchmark presents a comparative evaluation of cloning techniques in JavaScript and sheds light on their performance characteristics, pros, and cons to guide developers in choosing the most suitable method for their specific use cases.