Benchmark: JavaScript spread operator vs Object.assign performance with {} target obj

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

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches for merging objects in JavaScript: using the spread operator (`...`) and `Object.assign()`. The benchmark creates three objects, `firstObject`, `secondObject`, and a `finalObject`, which is then constructed by either spreading `firstObject` and `secondObject` into it or by using `Object.assign()` to merge them.

**Approaches Compared**

There are two approaches being compared:

1. **Using the spread operator (`...`)**: This approach uses the spread syntax (`...`) to create a new object by merging `firstObject` and `secondObject`. The syntax is: `{ ...firstObject, ...secondObject }`.
2. **Using `Object.assign()`**: This approach uses the `Object.assign()` method to merge `firstObject` and `secondObject` into a new object. 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 code.
		+ Can be more efficient because it avoids creating an intermediate object.
	* Cons:
		+ Only supported in ECMAScript 2018 and later versions (before that, use `Object.assign()` or another library).
2. **Using `Object.assign()`**
	* Pros:
		+ More widely supported across browsers and older JavaScript versions.
		+ Can be more predictable because it follows the language's built-in merging behavior.
	* Cons:
		+ Less concise code compared to the spread operator.

**Library Usage**

In both test cases, no libraries are explicitly mentioned. However, `Object.assign()` is a built-in method in JavaScript, so it doesn't require any external library inclusion.

**Special JS Features or Syntax**

Neither of these approaches utilizes special JavaScript features or syntax beyond what's available in modern JavaScript (ECMAScript 2018 and later versions). The spread operator was introduced in ECMAScript 2018, but the benchmark still uses older browsers that might not support it. If you wanted to use the latest spread syntax with this benchmark, you'd need to adjust the `DevicePlatform` and `OperatingSystem` settings.

**Other Alternatives**

If you want to explore other approaches for merging objects in JavaScript:

* You can also use object destructuring (`{ ...firstObject, ...secondObject }`) or function calls (`Object.fromEntries([['sampleData', 'Hello world'], ['moreData', 'foo bar']])`).
* Some libraries like Lodash (specifically, `_.merge()`) provide more flexible and expressive merging functions.

Keep in mind that these alternatives might have different performance characteristics or compatibility issues depending on the specific use case.

Related benchmarks:

JavaScript spread operator vs Object.assign performance with {} target obj (version: 0)

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

Created: 4 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):