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JavaScript Object.assign vs for in loop (-2)
(version: 0)
Comparing performance of:
Object.assign vs for in loop
Created:
one year ago
by:
Guest
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Tests:
Object.assign
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: { a: 9 } } Object.assign(a, b); Object.assign(b, a);
for in loop
const a = { x: 'xxx', y: 1, z: null } const b = { z: 1, u: 'uuu', v: { a: 9 } } for (let prop in b) a[prop] = b[prop]; for (let prop in a) b[prop] = a[prop];
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
Object.assign
for in loop
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:129.0) Gecko/20100101 Firefox/129.0
Browser/OS:
Firefox 129 on Windows
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<iframe src="https://measurethat.net/Embed?id=538564" width="100%" height="500px"></iframe>
Object.assign
7.5M/s
for in loop
7.5M/s
View exact numbers
Test name
Executions per second
✓
Object.assign
7,525,940 Ops/sec
for in loop
7,515,853 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**What is being tested?** The provided benchmark tests two approaches for copying objects: `Object.assign` and a manual `for in loop` approach. **Options compared:** 1. **Object.assign**: This method uses the spread operator (`{...obj}`) to create a new object, and then assigns properties from one object to another. 2. **Manual for in loop**: This approach iterates over the properties of an object using a `for in` loop, assigning values from one object to another. **Pros and Cons:** 1. **Object.assign**: * Pros: + Concise and readable + Efficient, as it creates a new object with a shallow copy of properties * Cons: + May be slower than the manual `for in loop` approach for very large objects or deep copying 2. **Manual for in loop**: * Pros: + Can be faster for large objects or deep copying, as it avoids creating a new object and only copies properties on-the-fly * Cons: + Less readable and maintainable due to the need to manage property iteration manually **Library/Functionality used:** 1. `Object.assign`: This is a built-in JavaScript method for assigning properties from one object to another. **Special JS feature/syntax:** None mentioned in this benchmark. **Other considerations:** * The manual `for in loop` approach may be more suitable for certain use cases, such as when dealing with large objects or deep copying. * The `Object.assign` method is generally considered more readable and maintainable, but may not be as efficient for very large objects or deep copying. **Alternatives:** 1. Other object assignment methods, such as `JSON.parse(JSON.stringify(obj))`, which can also achieve the same result. 2. Library functions like Lodash's `cloneDeep` or `merge`, which provide more comprehensive and flexible object copying solutions. 3. Other JavaScript engines or interpreters that may optimize or have different performance characteristics for these benchmarks. Note: The choice of approach depends on the specific use case, performance requirements, and personal preference.
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