Benchmark: JavaScript spread operator vs Object.assign performance vs. Native Assignment

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);
Using Native assignment.
const firstObject = { sampleData: 'Hello world' }; const secondObject = { moreData: 'foo bar' }; firstObject.moreData = 'foo bar';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign
Using Native assignment.

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's dive into the benchmark.

**Benchmark Overview**

The benchmark compares the performance of three ways to merge objects in JavaScript: using the spread operator (`...`), `Object.assign()`, and native assignment (`firstObject.moreData = 'foo bar';`). The goal is to determine which approach is the fastest.

**Options Compared**

1. **Using the spread operator (`...`)**:
	* Pros: Modern and concise syntax, easy to read and write.
	* Cons: May incur additional overhead due to the creation of a new object or array.
2. **Using `Object.assign()`**:
	* Pros: Standardized and widely supported, can handle more complex data merging scenarios.
	* Cons: Can be slower than native assignment for simple cases, has a higher memory footprint.
3. **Native Assignment (`firstObject.moreData = 'foo bar';`)**:
	* Pros: Fastest execution time among the three options, has the lowest memory overhead.
	* Cons: Non-standard syntax, may not be readable or maintainable for complex cases.

**Library Usage**

There is no explicit library usage in the benchmark definition. However, it's worth noting that `Object.assign()` relies on the `Object.prototype` property, which might not be the case in all browsers or environments.

**Special JavaScript Features/Syntax**

None mentioned in the provided data.

**Other Considerations**

* The benchmark uses a fixed number of objects to merge (`firstObject` and `secondObject`), which may not accurately represent real-world scenarios where objects have different structures and properties.
* The benchmark only tests simple assignment of a string value, ignoring more complex merging cases like array or object property updates.

**Alternatives**

Other alternatives for merging objects in JavaScript include:

* Lodash's `merge()` function
* Ramda's `merge` function
* JSON merge libraries like json-merge or json-migrate

These alternatives may offer different performance profiles, syntaxes, and feature sets compared to the options tested in this benchmark.

Related benchmarks:

JavaScript spread operator vs Object.assign performance vs. Native Assignment (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign vs Using Native assignment.

Created: 7 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Using Native assignment.

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):