Benchmark: JavaScript spread operator vs Object.assign performance QWERTY

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>

Previous results

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

Fastest: N/A

Slowest: N/A

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

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Let's dive into explaining what's being tested in this JavaScript microbenchmark.

**Benchmark Overview**

The provided benchmark compares two approaches to merge two objects: using the spread operator (`...`) and `Object.assign()`. The test case has two variations:

1. **Using the Spread Operator**: This method uses the syntax `{ ...firstObject, ...secondObject }` to merge the properties of `firstObject` and `secondObject`.
2. **Using Object.assign()**: This method uses the `Object.assign()` function to create a new object by copying properties from `firstObject` and `secondObject`.

**Options Comparison**

Here's a brief overview of each approach:

* **Using the Spread Operator**:
	+ Pros: Simple, concise syntax; creates a new object with merged properties.
	+ Cons: May lead to unexpected behavior if not used carefully (e.g., with primitive values).
* **Using Object.assign()**:
	+ Pros: More explicit and controlled way of merging objects; handles primitive values correctly.
	+ Cons: Requires creating an intermediate object using `Object.assign()`.

**Library Usage**

None in this benchmark. However, note that some versions of JavaScript (e.g., ECMAScript 2015+) introduced the spread operator (`...`), which is used here.

**Special JS Feature or Syntax**

Yes, the spread operator (`...`) is a special syntax feature introduced in ECMAScript 2015+. It allows objects to be merged using a concise syntax. This feature is also supported by modern browsers and Node.js versions.

**Other Considerations**

When choosing between these approaches:

* If you need a simple, concise way of merging objects with similar properties, the spread operator might be a good choice.
* However, if you're working with complex object structures or need more control over the merge process, `Object.assign()` is likely a better option.

**Alternative Approaches**

Other ways to merge objects in JavaScript include:

1. **Loose Object Assignment**: Using a function like `assign` from the `lodash` library: `_.assign(firstObject, secondObject)`.
2. **Method Chaining**: Using methods like `merge()` or `concat()` with objects: `firstObject.merge(secondObject)` (e.g., using the `merge` method from a library like Lodash).
3. **Recursion**: Merging objects by recursively iterating over properties and values.

Keep in mind that these alternatives might have different performance characteristics, syntax complexities, or use cases compared to the spread operator and `Object.assign()`.

Related benchmarks:

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

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

Created: 3 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

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):