Benchmark: JavaScript spread operator vs Object.assign performance ttt

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

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36

Browser/OS: Chrome 124 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	34097604.0 Ops/sec
Using Object.assign	9716053.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

The provided JSON represents two individual test cases, each with its own `Benchmark Definition`. These definitions describe how the JavaScript spread operator is compared to `Object.assign` in terms of performance.

**Test Cases:**

1. **Using the spread operator**: This test case uses the syntax `{...firstObject, ...secondObject}` to create a new object that combines the properties of two existing objects, `firstObject` and `secondObject`. The spread operator (`...`) is used to merge these objects.
2. **Using Object.assign**: This test case uses the `Object.assign()` method to achieve the same result as the spread operator. It creates an empty object `{}` and then assigns properties from `firstObject` and `secondObject` using the spread operator.

**Options Compared:**

* Spread Operator (`{...firstObject, ...secondObject}`)
* Object.assign() (`const finalObject = Object.assign({}, firstObject, secondObject);`)

**Pros and Cons of Each Approach:**

1. **Spread Operator:**
	* Pros:
		+ More concise and readable syntax
		+ Does not require creating an empty object as a target
		+ Often faster due to the language's internal optimization for merging objects
	* Cons:
		+ May have slightly worse performance in older browsers or those with limited support for modern JavaScript features
2. **Object.assign()**
	* Pros:
		+ More widely supported across different browsers and environments
		+ Can be used for other purposes beyond just object merging (e.g., assigning values to a target object)
	* Cons:
		+ Requires creating an empty object as a target, which can be unnecessary and less readable
		+ May have slightly worse performance compared to the spread operator

**Library/Utility Used:**

None, this benchmark only relies on built-in JavaScript features.

**Special JS Features/Syntax:**

The test case uses modern JavaScript syntax, specifically the spread operator (`{...firstObject, ...secondObject}`). This syntax is supported in most modern browsers and Node.js versions, but may not work in older environments.

**Other Alternatives:**

If you needed to achieve object merging without using either the spread operator or `Object.assign()`, other alternatives might include:

* Using a library like Lodash (`_.merge()` or `_.assign()`)
* Implementing a custom merging function
* Using a JSON merge strategy (e.g., `jsondiffpatch`)

Keep in mind that these alternatives would likely have different performance characteristics and may not be as concise or readable as the spread operator or `Object.assign()`.

Related benchmarks:

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

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

Created: one year 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

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