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JavaScript spread operator vs Object.assign (immutable) performance
(version: 0)
Comparing performance of:
Using the spread operator vs Using Object.assign
Created:
6 years ago
by:
Guest
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Tests:
Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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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 dive into the world of JavaScript microbenchmarks. **Benchmark Purpose and Description** The provided benchmark measures the performance difference between using the spread operator (`...`) and `Object.assign` (with an immutable object) when merging two objects in JavaScript. The test case is designed to compare these two approaches on a consistent dataset, ensuring that any observed differences are due to the specific implementation details of each method. **Options Compared** Two options are being compared: 1. **Spread Operator (`...`)**: This syntax was introduced in ECMAScript 2018 (ES9) and allows for easy object spreading using the three dots `...` before an object. 2. **`Object.assign()` with immutable objects**: The `Object.assign()` method takes multiple arguments and merges them into a single object, creating new properties for each object being merged. **Pros and Cons of Each Approach** ### Spread Operator (`...`) Pros: * More readable and concise syntax * Creates a shallow copy of the original object, ensuring immutability * Can be used with arrays as well Cons: * May incur additional overhead due to the spread operation * Not supported in older browsers or environments without ES9 support ### `Object.assign()` with immutable objects Pros: * Wide browser and environment support * Faster performance compared to the spread operator (due to optimized implementation) * Can be used for shallow copies of large objects Cons: * Less readable syntax, requiring more boilerplate code * Does not preserve the original object's structure or prototype chain **Library/Functionality Used** In this benchmark, `Object.assign()` is being compared. This is a built-in JavaScript function that has been part of the language since ECMAScript 2009. **Special JS Features/Syntax** There are no special JavaScript features or syntaxes being tested in this benchmark. **Alternative Approaches** Other alternatives for merging objects include: * Using `Object.create()` and then assigning properties to create a new object * Utilizing libraries like Lodash (`_merge`) or Ramda (`merge`) * Leveraging ES6 classes or computed property names for more complex merges For most use cases, the spread operator (`...`) has become a popular choice due to its concise syntax and immutability benefits. However, when performance is critical or older browsers are required, `Object.assign()` with immutable objects remains a viable option. Keep in mind that this benchmark specifically compares these two approaches on an immutable object merge scenario. Depending on the use case, other merging methods may be more suitable. When preparing benchmarks, consider factors such as: * Clear and concise test cases * Consistent environment and hardware configurations * Representative dataset sizes and complexity * Wide browser and environment support
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