Benchmark: Object.assign (with/without empty object) vs spread operator

Tests:

Object.assign
var params = { b:"hello", c: true, d:7 }; var other = Object.assign({ a: 2 }, params);
spread operator
var params = { b:"hello", c: true, d:7 }; var other = { a: 2, ...params };
Object.assign with empty object to start with
var params = { b:"hello", c: true, d:7 }; var other = Object.assign({}, { a: 2 }, params);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign
spread operator
Object.assign with empty object to start with

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is being tested, compared, and the pros/cons of each approach.

**Benchmark Overview**

The benchmark tests three different ways to perform an assignment operation using JavaScript's `Object.assign` method or the spread operator (`...`). The goal is to measure the performance difference between these approaches on a specific device (Chrome Mobile 73 on Android).

**Test Cases**

There are three test cases:

1. **`Object.assign` without any initial object**: This test case assigns an object with properties `a`, `b`, and `c` using the spread operator, which creates a new object.
```javascript
var params = { b: "hello", c: true, d: 7 };
var other = Object.assign(params);
```
2. **Spread Operator (`...`)**: This test case assigns an object with properties `a`, `b`, and `c` using the spread operator, which creates a new object.
```javascript
var params = { b: "hello", c: true, d: 7 };
var other = { a: 2, ...params };
```
3. **`Object.assign` with an empty initial object**: This test case assigns an object with properties `a`, `b`, and `c` using the spread operator, which creates a new object.
```javascript
var params = { b: "hello", c: true, d: 7 };
var other = Object.assign({}, { a: 2 }, params);
```
**Libraries Used**

None of the test cases use any external libraries.

**JavaScript Features/Syntax**

The tests use JavaScript syntax that is widely supported by modern browsers. Specifically:

* The spread operator (`...`) was introduced in ECMAScript 2015 (ES6) and is now widely supported.
* `Object.assign` has been part of the JavaScript language since its inception.

**Pros/Cons of Each Approach**

Here are some general pros and cons for each approach:

1. **`Object.assign` without any initial object**:
	* Pros: Simple, straightforward implementation.
	* Cons: Creates a new object, which can be slower than using an existing object as the target.
2. **Spread Operator (`...`)**:
	* Pros: More concise and expressive syntax.
	* Cons: Can create unnecessary objects if not used carefully (e.g., when creating a deep copy).
3. **`Object.assign` with empty initial object**:
	* Pros: Avoids creating an extra object, which can be beneficial for performance-critical code.
	* Cons: Requires the use of two function calls (`Object.assign()` and `{ ... }`) to create a new object.

**Other Alternatives**

If you need to perform assignments using other methods, consider:

1. **Using `Object.create()`**: This method creates a new object with the specified prototype chain.
```javascript
var params = { b: "hello", c: true, d: 7 };
var other = Object.create(Object.prototype)(params);
```
2. **Using `Array.prototype.slice()`**: This method creates a shallow copy of an array (which can be used to create an object).
```javascript
var params = [1, 2, 3];
var other = Array.prototype.slice.call(params);
```

Keep in mind that these alternatives may have different performance characteristics and use cases than the original methods being benchmarked.

Overall, the benchmark is testing three common ways to perform assignment operations using JavaScript's `Object.assign` method or the spread operator. The results will help identify which approach is faster on this specific device.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Linux; Android 9; Nokia 8 Sirocco) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.90 Mobile Safari/537.36

Browser/OS: Chrome Mobile 73 on Android

View result in a separate tab

Test name	Executions per second
Object.assign	1730213.4 Ops/sec
spread operator	970380.4 Ops/sec
Object.assign with empty object to start with	1610576.0 Ops/sec

Related benchmarks:

Object.assign (with/without empty object) vs spread operator (version: 0)

Comparing performance of: Object.assign vs spread operator vs Object.assign with empty object to start with

Created: 5 years ago by: Guest

Jump to the latest result

Object.assign

spread operator

Object.assign with empty object to start with

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):