Benchmark: JavaScript spread operator vs Object.assign performance 22477

Script Preparation code:

const obj1 = { a: "a" };
const obj2 = { b: "b" };

window.obj1 = obj1;
window.obj2 = obj2;

Tests:

Spread operator
const finalObject = { c: "a", ...obj1, d: "b", ...obj2 };
Object.assign
const finalObject = Object.assign({ c: "a" }, obj1, { d: "b" }, obj2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread operator
Object.assign

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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Let's dive into the provided JSON data for the JavaScript microbenchmark.

**Benchmark Overview**

The benchmark is designed to compare the performance of two methods in JavaScript: the spread operator (`...`) and `Object.assign()`. The test creates two objects, `obj1` and `obj2`, and then attempts to merge them into a new object using both methods. The goal is to determine which method is faster.

**Options Compared**

There are two options being compared:

1. **Spread Operator (`...`)**: This method uses the spread operator to expand the source objects into the target object.
```javascript
const finalObject = { c: "a" }, obj1, { d: "b" }, obj2;
finalObject = {
  ...obj1,
  ...{ d: "b" },
  c: "a"
};
```
**Pros and Cons**

* **Pros**: More concise and readable syntax. It's also a more modern and widely adopted method.
* **Cons**: May not be as efficient due to the overhead of creating new objects during expansion.

2. **Object.assign()**: This method uses the `Object.assign()` function to merge source objects into the target object.
```javascript
const finalObject = Object.assign({ c: "a" }, obj1, { d: "b" }, obj2);
```
**Pros and Cons**

* **Pros**: Can be more efficient for large datasets or when dealing with multiple source objects. It's also a widely supported method.
* **Cons**: Less concise syntax compared to the spread operator.

**Library Used**

In this benchmark, the `Object.assign()` function is used from the built-in JavaScript object. There is no additional library required.

**Special JS Feature or Syntax**

There are two instances of spread operator (`...`) used in this benchmark:

1. The first instance is used in the initial code to create `obj1` and `obj2`.
```javascript
const obj1 = { a: "a" };
const obj2 = { b: "b" };

window.obj1 = obj1;
window.obj2 = obj2;
```
The spread operator is not used for merging objects in this case.

2. The second instance is used in the benchmark script to create `finalObject`.
```javascript
const finalObject = {
  c: "a",
  ...obj1,
  d: "b"
};
```
**Other Alternatives**

Some alternative methods for merging objects include:

* Using a library like Lodash or Underscore.js, which provide more efficient and flexible ways to merge objects.
* Using the `merge()` function from the `lodash.merge` module (e.g., `const _ = require('lodash'); const finalObject = _.merge({}, obj1, { d: "b" }, obj2);`)
* Implementing a custom merging function using loops or recursive functions.

However, in this benchmark, only the spread operator and `Object.assign()` are being compared for performance.

Related benchmarks:

JavaScript spread operator vs Object.assign performance 22477 (version: 0)

Comparing performance of: Spread operator vs Object.assign

Created: 3 years ago by: Guest

Jump to the latest result

Spread operator

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):