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Array cloning: slice vs spread
(version: 0)
Comparing performance of:
slice vs spread
Created:
5 years ago
by:
Guest
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Tests:
slice
const arr = [1, 2, 'hello', true]; const arr2 = arr.slice();
spread
const arr = [1, 2, 'hello', true]; const arr2 = [...arr];
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
slice
spread
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks! **What is tested on the provided JSON?** The JSON represents a benchmark test case that compares two approaches for cloning an array: using the `slice()` method and using the spread operator (`...`). The benchmark tests which approach is faster. **Options compared** There are two options being compared: 1. **`slice()`**: This method creates a shallow copy of the original array, returning a new array with references to the same elements as the original array. 2. **Spread operator (`...`)**: This syntax creates a new array by copying all elements from the original array. **Pros and Cons** **`slice()`**: Pros: * Widely supported in older browsers (IE8+) * Faster execution time for small arrays * More predictable behavior Cons: * Creates a shallow copy, which can lead to unexpected behavior when modifying the cloned array * Can be slower for large arrays due to the overhead of creating multiple objects **Spread operator (`...`)** Pros: * Creates a new, truly independent copy of the original array * More memory-efficient than `slice()` * Supports larger arrays without significant performance degradation Cons: * Requires newer browsers (IE11+ or modern JavaScript engines) * Can be slower for very large arrays due to memory allocation overhead * May lead to unexpected behavior if not used carefully in certain contexts **Library and its purpose** There are no libraries involved in this benchmark. The `slice()` method is a built-in JavaScript function, while the spread operator (`...`) was introduced in ECMAScript 2015 (ES6). **Special JS feature or syntax** The spread operator (`...`), also known as "rest parameter" or "spread syntax", was introduced in ECMAScript 2015 (ES6) and is supported by most modern JavaScript engines. **Other considerations** * Array cloning can be an expensive operation, especially for large arrays. This benchmark focuses on comparing the performance of different methods. * The benchmark only tests small arrays with a fixed number of elements. For larger arrays or more complex use cases, other factors like memory usage and garbage collection might become relevant. **Other alternatives** If you're interested in testing array cloning for larger arrays or more complex scenarios, consider exploring: 1. **`Array.prototype.map()`**: Creates a new array by mapping each element to a new value. 2. **`Array.prototype.reduce()`**: Creates a new array by reducing an array of values into a single output value. 3. **Custom array cloning libraries**: There are libraries like Lodash or Immutable.js that provide optimized array cloning functions for specific use cases. Feel free to ask if you have any further questions!
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