Benchmark: Objects spread vs object assign with large object

Tests:

Object.assign

// Object.assign
function createObject(fillValue) {
    return Object.fromEntries(new Array(1024*12).fill(fillValue).map((value, index) => {
        return [fillValue + index, fillValue + index];
    }));
}

const params = createObject('params');
const other = Object.assign(createObject('assign'), params);

​x
 
// Object.assignfunction createObject(fillValue) {    return Object.fromEntries(new Array(1024*12).fill(fillValue).map((value, index) => {        return [fillValue + index, fillValue + index];    }));}​const params = createObject('params');const other = Object.assign(createObject('assign'), params);​

spread operator

// spread operator
function createObject(fillValue) {
    return Object.fromEntries(new Array(1024*12).fill(fillValue).map((value, index) => {
        return [fillValue + index, fillValue + index];
    }));
}

const params = createObject('params');
const other = {...createObject('spread'), ...params};

 
// spread operatorfunction createObject(fillValue) {    return Object.fromEntries(new Array(1024*12).fill(fillValue).map((value, index) => {        return [fillValue + index, fillValue + index];    }));}​const params = createObject('params');const other = {...createObject('spread'), ...params};

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory

Test case name	Result
Object.assign
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.79 Safari/537.36

Browser/OS: Chrome 100 on Windows

View result in a separate tab

Test name	Executions per second
Object.assign	40.6 Ops/sec
spread operator	31.4 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 5 months ago):

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

Benchmark Overview

The benchmark compares two ways to create large objects in JavaScript: using the traditional Object.assign() method and the new ES6 spread operator (...).

Script Preparation Code

The script preparation code is not provided, but it's assumed that both test cases use the same underlying logic to generate a large object with 1024*12 properties.

For the "spread operator" test case, the code uses Object.fromEntries() method, which is a part of the JavaScript standard library. This method creates an object from an array of key-value pairs.

Library Used:

In this case, the Object.fromEntries() method is used as a helper function to generate the large object.

Test Cases

There are two test cases:

"Object.assign": This test case uses the traditional Object.assign() method to create the large object.
"spread operator": This test case uses the new ES6 spread operator (...) to create the large object.

Pros and Cons of Each Approach

Object.assign():
- Pros: widely supported, efficient in older browsers (before Chrome 100).
- Cons: can be slower due to the method call overhead.
Spread Operator (...):
- Pros: concise, faster, and more modern syntax.
- Cons: not supported in older browsers (before Chrome 100).

Other Considerations

Performance: The spread operator is generally faster than Object.assign() due to its simpler syntax and lack of method call overhead.
Readability: Both approaches are relatively readable, but the spread operator provides a more concise way to create large objects.

Alternatives

If you need to support older browsers (before Chrome 100), you may consider using other libraries or polyfills to implement the spread operator. Some alternatives include:

Lodash's _.assign() method
A library like object-assign for compatibility with older browsers

Keep in mind that if you're targeting modern browsers and want to take advantage of the spread operator, it's likely a better choice.

For those interested in learning more about JavaScript features or syntax, some notable mentions include:

Object.fromEntries(): introduced in ECMAScript 2017.
... spread operator: introduced in ECMAScript 2015 (ES6).

These features have improved performance and readability in modern JavaScript development.

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares two ways to create large objects in JavaScript: using the traditional `Object.assign()` method and the new ES6 spread operator (`...`).

**Script Preparation Code**

The script preparation code is not provided, but it's assumed that both test cases use the same underlying logic to generate a large object with 1024*12 properties.

For the "spread operator" test case, the code uses `Object.fromEntries()` method, which is a part of the JavaScript standard library. This method creates an object from an array of key-value pairs.

**Library Used:**

In this case, the `Object.fromEntries()` method is used as a helper function to generate the large object.

**Test Cases**

There are two test cases:

1. **"Object.assign"**: This test case uses the traditional `Object.assign()` method to create the large object.
2. **"spread operator"**: This test case uses the new ES6 spread operator (`...`) to create the large object.

**Pros and Cons of Each Approach**

* **`Object.assign()`**:
	+ Pros: widely supported, efficient in older browsers (before Chrome 100).
	+ Cons: can be slower due to the method call overhead.
* **Spread Operator (`...`)**:
	+ Pros: concise, faster, and more modern syntax.
	+ Cons: not supported in older browsers (before Chrome 100).

**Other Considerations**

* **Performance**: The spread operator is generally faster than `Object.assign()` due to its simpler syntax and lack of method call overhead.
* **Readability**: Both approaches are relatively readable, but the spread operator provides a more concise way to create large objects.

**Alternatives**

If you need to support older browsers (before Chrome 100), you may consider using other libraries or polyfills to implement the spread operator. Some alternatives include:

* Lodash's `_.assign()` method
* A library like `object-assign` for compatibility with older browsers

Keep in mind that if you're targeting modern browsers and want to take advantage of the spread operator, it's likely a better choice.

For those interested in learning more about JavaScript features or syntax, some notable mentions include:

* `Object.fromEntries()`: introduced in ECMAScript 2017.
* `...` spread operator: introduced in ECMAScript 2015 (ES6).

These features have improved performance and readability in modern JavaScript development.

Related benchmarks:

Objects spread vs object assign with large object (version: 1)

Compare the new ES6 spread operator with the traditional Object.assign() method large object

Comparing performance of: Object.assign vs spread operator

Created: 3 years ago by: Registered User

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