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JavaScript spread operator vs concat
(version: 0)
Comparing performance of:
Using the spread operator vs Using Object.assign
Created:
4 years ago
by:
Guest
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Tests:
Using the spread operator
const firstObject = [1,2,3] const secondObject = [3,4,5] const finalObject = [ ...firstObject, ...secondObject ];
Using Object.assign
const firstObject = [1,2,3] const secondObject = [3,4,5] const finalObject = [].concat(firstObject).concat(secondObject)
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Suite status:
<idle, ready to run>
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Test case name
Result
Using the spread operator
Using Object.assign
Fastest:
N/A
Slowest:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested, compared, and discussed. **What is being tested?** The benchmark measures the performance difference between two ways of merging arrays in JavaScript: using the spread operator (`...`) and `Object.assign`. The test cases are designed to create a new array by combining two existing arrays, `firstObject` and `secondObject`, with the desired placement of elements. **Options compared:** Two approaches are compared: 1. **Using the spread operator**: This method uses the syntax `const finalObject = [...firstObject, ...secondObject];`. The spread operator (`...`) is used to expand an array into individual elements. 2. **Using Object.assign**: This method uses the `concat()` method in combination with `Object.assign()`: `const finalObject = [].concat(firstObject).concat(secondObject);`. **Pros and Cons:** * **Using the spread operator**: + Pros: concise, readable, and efficient for merging arrays. + Cons: not all browsers support the spread operator (some older versions of Internet Explorer), and it may be slower due to the parsing overhead. * **Using Object.assign**: + Pros: widely supported across modern browsers, but less readable than using the spread operator. + Cons: requires more code, which can lead to a larger performance hit. **Other considerations:** * The benchmark assumes that the input arrays `firstObject` and `secondObject` have the same length. If they don't, the results may vary depending on how JavaScript handles partial merging. * It's worth noting that in modern JavaScript, using `Array.prototype.push()` or `concat()` with an array is generally faster than using the spread operator. **Library usage:** There is no explicit library used in these test cases. The `Object.assign()` method is a built-in JavaScript function, and the spread operator (`...`) was introduced in ECMAScript 2015 (ES6). **Special JS feature or syntax:** No special features or syntax are required to run these tests. They are designed to be platform-agnostic and focus on comparing different approaches for array merging. **Alternatives:** If you're looking for alternative methods for merging arrays, here are a few options: * Using `Array.prototype.push()` with an array: `const finalObject = [...firstObject].concat(secondObject);` * Using a library like Lodash's `merge` function * Using the `reduce()` method to merge two arrays into one However, it's worth noting that the spread operator and `Object.assign()` are among the most efficient and widely supported methods for merging arrays in modern JavaScript.
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