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slice vs spread asdf
(version: 0)
Comparing performance of:
slice vs spread
Created:
7 years ago
by:
Guest
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Tests:
slice
var arr = [1,2,3,4,5,6,7,8,9,10]; var copy = arr.slice(0);
spread
var arr = [1,2,3,4,5,6,7,8,9,10]; var copy = [ ...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 on MeasureThat.net. **What is being tested?** The provided benchmark measures the performance difference between two approaches: using the `slice()` method and using the spread operator (`[ ... ]`) to create a copy of an array in JavaScript. The test cases are identical, with only the implementation details differing between the "slice" and "spread" options. **Options compared** There are two main options being compared: 1. **`slice()` method**: This is a built-in method in JavaScript that returns a shallow copy of an array. It's commonly used to create a new array that references the same elements as the original array. 2. **Spread operator (`[ ... ]`)**: This is a syntax sugar introduced in ECMAScript 2015 (ES6) that allows you to create a new array by iterating over the elements of an existing array and copying them into a new array. **Pros and Cons** * **`slice()` method**: + Pros: - Well-established and widely supported - Faster execution time, as it doesn't need to iterate over the elements like the spread operator does + Cons: - Can be slower for large arrays, as it needs to allocate memory for the new array - Creates a shallow copy, which might not be desirable in all cases (e.g., when working with objects that contain references) * **Spread operator (`[ ... ]`)**: + Pros: - More modern and concise syntax - Can handle arrays of arbitrary length without performance issues + Cons: - Slower execution time compared to the `slice()` method, due to the iteration over elements - Not as widely supported in older browsers or environments **Library and purpose** There are no libraries mentioned in this benchmark. The focus is solely on comparing the two array creation methods. **Special JS feature or syntax** The spread operator (`[ ... ]`) is a relatively new feature introduced in ES6, which allows you to create new arrays by iterating over existing arrays. It's a concise and expressive way to create copies of arrays, but its performance might be slightly lower compared to the `slice()` method. **Other alternatives** If you're looking for alternative ways to create array copies, here are some options: * **`Array.prototype.map()`**: While not directly creating an array copy, this method can be used to create a new array with transformed elements. For example: `arr.map((element) => element * 2)` would create a new array with doubled values. * **`Array.prototype.reduce()`**: Similar to `map()`, but with additional flexibility in the transformation process. * **Manual iteration**: You can use a simple loop to iterate over the elements of an array and push them into a new array. For example: `var copy = []; for (var i = 0; i < arr.length; i++) { copy.push(arr[i]); }` Keep in mind that these alternatives might have different performance characteristics compared to the `slice()` method or spread operator, depending on your specific use case and requirements.
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