Benchmark: Object.assign vs apread

Script Preparation code:

var o1 = { a: 1 };
var o2 = { b: 2 }

Tests:

Object.assign
var o3 = Object.assign({}, o1, o2);
Spread
var o3 = {...o1, ...o2}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign
Spread

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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I'll break down the provided benchmark and explain what's being tested, compared, and their pros/cons.

**Benchmark Overview**

The benchmark compares two approaches to merge objects in JavaScript: `Object.assign()` and the spread operator (`...`). The test cases use sample object literals `o1` and `o2`, which are defined in the "Script Preparation Code" section of the benchmark definition.

**What's being tested?**

In each test case, a new object `o3` is created by merging `o1` and `o2`. The difference lies in the method used to merge these objects:

* In the first test case (`Object.assign()`), an explicit call to `Object.assign(o3, o1, o2)` is made.
* In the second test case (spread operator), a more concise syntax `o3 = {...o1, ...o2}` is used.

**Comparison and pros/cons**

Here's a brief comparison of these two approaches:

### Object.assign()

Pros:

1. **Explicitness**: The code is explicit about what objects are being merged.
2. **Consistency**: This approach is consistent with the `Object.assign()` method, which can be useful for developers familiar with it.

Cons:

1. **Verbosity**: The code requires calling an additional function and passing arguments.
2. **Performance overhead**: Creating a new object and assigning properties to it might introduce some unnecessary overhead compared to the spread operator.

### Spread Operator

Pros:

1. **Conciseness**: The syntax is more compact and readable.
2. **Performance**: This approach is likely to be faster since it avoids creating an intermediate object.

Cons:

1. **Less explicitness**: Some developers might find the spread operator less intuitive, especially when dealing with nested objects.
2. **Browser support**: While modern browsers support the spread operator, older versions might not. However, this benchmark uses Chrome 107, which supports it.

**Library usage**

There is no library explicitly mentioned in these test cases. The `Object.assign()` method is a built-in JavaScript function, and the spread operator is also a native JavaScript feature introduced in ECMAScript 2018 (ES2018).

**Special JS feature or syntax**

The benchmark uses the spread operator (`...`), which was introduced in ES2018. This feature allows for more concise object merging.

**Alternatives**

Other alternatives for merging objects include:

1. **Object.create()**: An older method that creates a new object and assigns properties to it, but it's not as concise or intuitive as the spread operator.
2. **Array.prototype.reduce()**: Another approach involves using `reduce()` on an array of key-value pairs. While this can be useful in certain situations, it's less common for simple object merging.

Keep in mind that benchmarking JavaScript performance should consider factors like device platform, operating system, and browser version to ensure accurate results. MeasureThat.net is a great resource for such benchmarks!

Related benchmarks:

Object.assign vs apread (version: 0)

Comparing performance of: Object.assign vs Spread

Created: 3 years ago by: Guest

Jump to the latest result

Object.assign

Spread

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):