Benchmark: Spread vs Object.assign vs Object.keys

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);
Not merging
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = {} Object.keys(firstObject) .concat(Object.keys(secondObject)) .forEach(key => {finalObject[key] = firstObject[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
Not merging

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided benchmark, hosted on MeasureThat.net, compares the performance of three approaches to merge objects in JavaScript: using the spread operator (`...`), `Object.assign()`, and manually iterating over keys without merging.

**Options Compared**

1. **Using the Spread Operator**: This method uses the syntax `const finalObject = { ...firstObject, ...secondObject };`. It's a concise way to merge objects by spreading their properties into a new object.
2. **Using `Object.assign()`**: This method uses the `Object.assign()` function to merge two objects: `const finalObject = Object.assign(firstObject, secondObject);`. It's an older method that's still widely used.
3. **Not Merging**: This approach manually iterates over keys without merging: `const finalObject = {}; Object.keys(firstObject).concat(Object.keys(secondObject)).forEach(key => {finalObject[key] = firstObject[key] || secondObject[key]});`. It's a more verbose way to achieve the same result.

**Pros and Cons of Each Approach**

1. **Using the Spread Operator**:
	* Pros: Concise, efficient, and widely supported.
	* Cons: May be less predictable than other methods in certain situations (e.g., when dealing with inherited properties).
2. **Using `Object.assign()`**:
	* Pros: Well-established, reliable, and compatible with older browsers.
	* Cons: Can be slower than the spread operator due to its overhead, especially for large objects.
3. **Not Merging**:
	* Pros: No dependencies on external libraries or functions, making it a good option for simple cases or when compatibility is crucial.
	* Cons: More verbose and less efficient compared to other methods.

**Library Used (if any)**

None in this benchmark.

**Special JS Feature/Syntax**

The spread operator (`...`) was introduced in ECMAScript 2018 and has become a standard feature in modern JavaScript. It allows for more concise object creation and merging.

**Other Considerations**

When choosing an approach, consider the following factors:

* Performance: For large objects or high-performance applications, using `Object.assign()` might be a better choice due to its potential stability and predictability.
* Code readability: Using the spread operator can make code more concise and readable for simple cases. However, for complex merges with many properties, manually iterating over keys without merging may be more suitable.
* Compatibility: Ensure that your target browsers or environments support the chosen approach.

**Alternatives**

If you want to explore alternative methods, consider:

1. Using `Object.create()` with the spread operator (`const finalObject = Object.create(null) { ...firstObject, ...secondObject };`)
2. Using a library like Lodash's `mergeDeep()` function
3. Using a custom implementation based on your specific requirements and performance considerations

Related benchmarks:

Spread vs Object.assign vs Object.keys (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign vs Not merging

Created: 6 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Not merging

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):