Benchmark: Object assign vs spread

Script Preparation code:

const item1 = { a:1, b:2 };
const item2 = { c:3, d:4 };

Tests:

Spread
const item1 = { a:1, b:2 }; const item2 = { c:3, d:4 }; const item3 = { ...item1, ...item2 };
Assign merge
const item1 = { a:1, b:2 }; const item2 = { c:3, d:4 }; const item3 = Object.assign(item1, item2);
Assign create
const item1 = { a:1, b:2 }; const item2 = { c:3, d:4 }; const item3 = Object.assign({}, item1, item2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
Assign merge
Assign create

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

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Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided JSON represents a benchmark for comparing three approaches to merge two objects in JavaScript:

1. **Spread Operator**: `const item3 = { ...item1, ...item2 };`
2. **Object.assign()**: `const item3 = Object.assign(item1, item2);`
3. **Object creation and assignment**: `const item3 = Object.assign({}, item1, item2);`

**What is being tested?**

The benchmark measures the performance of these three approaches on a specific test case, where two objects (`item1` and `item2`) are merged into a third object (`item3`). The tests compare the execution time of each approach.

**Options compared:**

* **Spread Operator**: uses the spread operator (`...`) to merge two objects.
* **Object.assign()**: uses the `Object.assign()` method to merge two objects.
* **Object creation and assignment**: creates a new object using `Object.assign()` with an initial object `{}` as the first argument, and then merges `item1` and `item2` into it.

**Pros and Cons of each approach:**

* **Spread Operator**:
	+ Pros: concise, efficient, and widely supported.
	+ Cons: can be slower due to the overhead of parsing the spread operator, especially for large objects.
* **Object.assign()**:
	+ Pros: reliable, well-documented, and widely supported.
	+ Cons: requires creating a new object with an initial value (in this case, `{}`), which can be slower for very large objects.
* **Object creation and assignment**:
	+ Pros: avoids the overhead of parsing the spread operator, but still provides a clear and explicit way to merge objects.
	+ Cons: requires more memory allocation and can be slower due to the additional object creation step.

**Library usage:**

None of these approaches rely on any specific library. They are all built-in JavaScript features.

**Special JS feature or syntax:**

The spread operator (`...`) is a relatively new addition to JavaScript, introduced in ECMAScript 2018 (ES2018). It provides a concise way to merge objects and arrays.

**Other alternatives:**

If you're interested in exploring alternative approaches, consider:

* Using `JSON.parse()` and `JSON.stringify()` to merge objects.
* Implementing your own custom merging function using recursion or iteration.
* Using third-party libraries like Lodash or Ramda for more advanced object manipulation and merging capabilities.

Keep in mind that these alternatives may come with additional overhead, complexity, or memory requirements.

Related benchmarks:

Object assign vs spread (version: 0)

Comparing performance of: Spread vs Assign merge vs Assign create

Created: 5 years ago by: Guest

Jump to the latest result

Spread

Assign merge

Assign create

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):