Benchmark: JavaScript merge properties

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 assignment
const firstObject = { sampleData: "Hello world" }; const secondObject = { moreData: "foo bar" }; const finalObject = {}; for (const key in firstObject) { finalObject[key] = firstObject[key]; } for (const key in secondObject) { finalObject[key] = secondObject[key]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign
Using 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 and analyze what's being tested.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that compares three different approaches to merge two objects: using the spread operator (`...`), `Object.assign()`, and manual assignment (iteration).

**Options Compared**

1. **Using the spread operator**: This approach uses the syntax `${object1} {...object2}` to merge two objects, creating a new object with all properties from both input objects.
2. **Using Object.assign()**: This method takes multiple source objects and merges them into a target object using the `Object.assign()` function.
3. **Manual assignment**: This approach iterates over the keys of one object and assigns its values to another object, manually merging the two inputs.

**Pros and Cons**

1. **Using the spread operator**:
	* Pros: concise, expressive, and efficient for simple object merges.
	* Cons: not supported in older browsers or versions of JavaScript, may lead to unexpected behavior if used incorrectly (e.g., with nested objects).
2. **Using Object.assign()**:
	* Pros: widely supported across modern browsers and JavaScript versions, provides a safe way to merge objects by creating a shallow copy.
	* Cons: can be less efficient than the spread operator for large object merges, may lead to unexpected behavior if used incorrectly (e.g., with nested objects).
3. **Manual assignment**:
	* Pros: widely supported across modern browsers and JavaScript versions, allows for fine-grained control over merge operations.
	* Cons: verbose, error-prone, and less efficient than the spread operator or `Object.assign()`.

**Library**

None of these approaches rely on a specific library. However, if you're interested in using a library that provides a similar merging functionality, you might consider using Lodash's `merge()` function or other object merge libraries.

**Special JS Features or Syntax**

The benchmark uses the spread operator (`...`) and template literals (`"${object1}"`), which are relatively modern JavaScript features introduced in ECMAScript 2015 (ES6). These features provide a concise and expressive way to perform object merges, but may not be supported in older browsers or versions of JavaScript.

**Other Considerations**

When choosing an approach for merging objects, consider the following factors:

* **Browser support**: If you need to support older browsers or versions of JavaScript, use `Object.assign()` or manual assignment.
* **Efficiency**: For large object merges, the spread operator or `Object.assign()` might be more efficient than manual assignment.
* **Readability and maintainability**: Use a consistent approach throughout your codebase and consider the readability benefits of using the spread operator or `Object.assign()`.

Other alternatives for merging objects include:

* Using a library like Lodash's `merge()` function
* Utilizing the `reduce()` method to merge objects
* Implementing a custom object merge algorithm

Keep in mind that these alternatives might introduce additional dependencies, complexity, or performance overhead compared to the original approaches.

Related benchmarks:

JavaScript merge properties (version: 0)

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

Created: 2 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Using 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):