Benchmark: object assign mutate vs object assign new object

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign(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

Latest run results:

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

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Let's break down the benchmark and its results.

**Benchmark Overview**

The benchmark measures the performance of two approaches to merge two objects: using the spread operator (`{ ... }`) and using `Object.assign()`. The test creates two objects, `firstObject` and `secondObject`, with sample data, and then attempts to merge them into a single object, `finalObject`.

**Options Compared**

The benchmark compares two options:

1. **Using the Spread Operator**: This approach uses the spread operator (`{ ... }`) to create a new object that merges the properties of `firstObject` and `secondObject`. The syntax is: `const finalObject = { ... firstObject, ... secondObject };`
2. **Using Object.assign()**: This approach uses the `Object.assign()` method to merge the two objects. The syntax is: `const finalObject = Object.assign({}, firstObject, secondObject);`

**Pros and Cons of Each Approach**

1. **Using the Spread Operator**:
	* Pros:
		+ More concise and readable syntax.
		+ Less error-prone than using `Object.assign()`.
	* Cons:
		+ May not be as efficient for large objects due to the creation of a new object with spread operators.
2. **Using Object.assign()**:
	* Pros:
		+ Can be more efficient for large objects since it avoids creating a new object.
	* Cons:
		+ Less readable and more error-prone than using the spread operator.

**Library Used**

In this benchmark, there is no specific library used that requires explanation. However, it's worth noting that some browsers may optimize or polyfill `Object.assign()` to improve performance.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax mentioned in this benchmark. The test uses standard JavaScript syntax for object merging.

**Other Considerations**

When evaluating the performance of these two approaches, consider factors such as:

* Object size: For large objects, `Object.assign()` might be more efficient due to reduced overhead from creating a new object.
* Performance-critical code: In performance-critical code paths, every optimization counts. In this case, using `Object.assign()` might provide a slight performance advantage.

**Alternatives**

Other alternatives for merging objects include:

1. **Using the `Object.concat()` method**: This method was available in older browsers but has been deprecated in modern standards.
2. **Using the `JSON.merge()` function**: Not a standard JavaScript method, this would require polyfills or browser-specific implementation.
3. **Implementing your own merge function**: Depending on performance and code readability requirements, you might choose to implement a custom merge function.

Keep in mind that for most use cases, using the spread operator (`{ ... }`) is likely the preferred approach due to its conciseness, readability, and reduced error risk. However, if specific optimizations or performance considerations dictate otherwise, `Object.assign()` can be used instead.

Related benchmarks:

object assign mutate vs object assign new object (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):