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Array concat vs array spread
(version: 0)
Comparing performance of:
Concat vs Spread
Created:
5 years ago
by:
Guest
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Tests:
Concat
let target = new Array(25).fill(0); const items = new Array(25).fill(0); for(let i=0; i<10000; ++i){ target = target.concat(items); }
Spread
let target = new Array(25).fill(0); const items = new Array(25).fill(0); for(let i=0; i<10000; ++i){ target = {...target, ...items}; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
Concat
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 being tested?** The provided JSON represents a benchmark test that compares the performance of two approaches to concatenate arrays in JavaScript: `Array.concat()` and the spread operator (`...`). The benchmark is designed to measure which approach is faster for large array concatenations. **Options compared:** 1. **`Array.concat()`**: This method takes an existing array as an argument and returns a new array that contains all elements from both the original array and the new array. 2. **Spread operator (`...`)**: This syntax allows you to spread the elements of one or more arrays into another array. **Pros and Cons:** * `Array.concat()`: + Pros: - Widely supported across different browsers and versions. - Can be used with other array methods like `push()` and `slice()`. + Cons: - Creates a new array on each concatenation, which can lead to memory allocation overhead. - May not be as efficient for large datasets due to the creation of intermediate arrays. * Spread operator (`...`): + Pros: - More concise and expressive syntax. - Only creates one copy of the resulting array, reducing memory allocation overhead. - Can be used with other spread operators to merge multiple arrays into a single array. + Cons: - May not be supported across older browsers or versions (although it's been widely adopted). - Can lead to unexpected behavior if not used carefully. **Other considerations:** * Both approaches are generally suitable for small to medium-sized datasets. For very large datasets, the spread operator might have a slight edge due to its reduced memory allocation overhead. * The benchmark results show that the spread operator outperforms `Array.concat()` in this specific test case. However, it's essential to note that these results may vary depending on the specific use case and dataset size. **Library or special JS feature:** There is no library used in this benchmark. It only relies on built-in JavaScript features. **Special JS feature or syntax:** The spread operator (`...`) is a relatively recent addition to JavaScript, introduced in ECMAScript 2015 (ES6). It's a concise way to merge arrays or objects into new collections, and its usage has become increasingly popular among developers.
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