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Spread vs Iteration
(version: 2)
Comparing performance of:
Spread vs ForEach vs Object.assign
Created:
3 years ago
by:
Registered User
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Tests:
Spread
const a = { a: 1 }; const b = { b: 1, c: 2, d: 3, e: 4, f: 5, g: 6 }; const c = { ...a, ...b };
ForEach
const a = { a: 1 }; const b = { b: 1, c: 2, d: 3, e: 4, f: 5, g: 6 }; Object.entries(b).forEach(([key, value]) => { a[key] = value; });
Object.assign
const a = { a: 1 }; const b = { b: 1, c: 2, d: 3, e: 4, f: 5, g: 6 }; const c = Object.assign({}, a, b);
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
Spread
ForEach
Object.assign
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll provide an explanation of the benchmark, its options, and other considerations. **What is tested?** The provided JSON represents a JavaScript microbenchmarking test suite. The test measures the performance difference between three methods to merge two objects: spread syntax (`...`), `forEach`, and `Object.assign`. **Options compared:** 1. **Spread syntax**: This method uses the spread operator (`...`) to create a new object by merging two existing objects. 2. **ForEach**: This method iterates over the properties of one object using `Object.entries()` and assigns each property value to another object. 3. **Object.assign()**: This method creates a new object by copying all enumerable own properties from one or more source objects. **Pros and Cons:** * **Spread syntax**: + Pros: Concise, readable, and efficient for small to medium-sized objects. + Cons: May not be suitable for very large objects due to performance overhead. * **ForEach**: + Pros: Flexible, can handle complex merge logic, and works well with large objects. + Cons: Iteration-based approach can lead to slower performance compared to other methods. * **Object.assign()**: + Pros: Widely supported, efficient for small to medium-sized objects, and easy to use. + Cons: Can be less readable than spread syntax or forEach, especially for complex merge logic. **Library/Functionality used:** The benchmark uses the `Object.entries()` method, which is a part of the ECMAScript standard. This method returns an array of a given object's own enumerable string-keyed property [key, value] pairs. No specific libraries are required beyond the built-in JavaScript objects and methods. **Special JS feature/syntax:** The benchmark uses the spread syntax (`...`), which is a relatively recent addition to the ECMAScript standard (ES6). This syntax allows for concise object creation by merging two or more objects into one. Other alternatives: * **Destructuring assignment**: Another way to merge objects using destructuring assignment, e.g., `const c = { ...a, ...b };`. * **Object spread operator with Object.create()**: Using `Object.create()` and spread syntax together, e.g., `const c = Object.create(null).spread({ a: 1 }, { b: 1 });`. Keep in mind that these alternatives might not be as widely supported or efficient as the original methods used in this benchmark.
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