Benchmark: Object.assign vs direct assignment multiple properties

Script Preparation code:

var data = {};

Tests:

Direct Assignment
for(var i = 0; i < 10000; i++) { data[`prop_${i}`] = true; data[`prop_${i}1`] = true; data[`prop_${i}2`] = true; data[`prop_${i}3`] = true; data[`prop_${i}4`] = true; data[`prop_${i}5`] = true; data[`prop_${i}6`] = true; data[`prop_${i}7`] = true; data[`prop_${i}8`] = true; data[`prop_${i}9`] = true; data[`prop_${i}10`] = true; data[`prop_${i}11`] = true; data[`prop_${i}12`] = true; }
Object.assign
for(var i = 0; i < 10000; i++) { var propName = `prop_${i}`; Object.assign(data, { [propName]: true }); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Direct Assignment
Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser/OS: Chrome 125 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Direct Assignment	60.4 Ops/sec
Object.assign	240.7 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The provided benchmark compares two approaches for assigning multiple properties to an object: `Object.assign` and direct assignment (also known as "chaining" or "dot notation"). The test creates a large array of objects with 10 properties each, assigns the value `true` to each property using both methods, and measures their performance.

**What is being tested?**

The benchmark tests the performance difference between using the `Object.assign()` method to assign multiple properties to an object versus directly assigning each property individually (using dot notation or "chaining").

**Options Compared:**

1. **Direct Assignment**: Assigning individual properties to an object using dot notation (`data.prop_name = true;`).
2. **Object.assign() Method**: Using the `Object.assign()` method to assign multiple properties to an object in a single operation.

**Pros and Cons of each approach:**

* **Direct Assignment**:
	+ Pros: Simple, concise syntax.
	+ Cons: Can be slower due to repeated property lookups on the target object.
* **Object.assign() Method**:
	+ Pros: Efficient for assigning multiple properties in a single operation, reducing overhead due to repeated property lookups.
	+ Cons: Requires creating an object with the desired properties and using the `assign()` method, which can be more verbose.

In general, the `Object.assign()` method is preferred when assigning large numbers of properties, as it reduces the number of property lookups on the target object. However, for small datasets or performance-critical code, direct assignment might still be a viable option due to its simplicity and concise syntax.

**Library and Purpose:**

In this benchmark, `Object.assign()` is a built-in JavaScript method that allows you to copy properties from one or more source objects to a target object.

**Special JS feature or syntax:**

There are no special features or syntaxes mentioned in the provided benchmark.

**Alternative approaches:**

Other approaches for assigning multiple properties to an object include:

* Using the spread operator (`{ ...obj }`).
* Utilizing `Object.create()` and `Object.assign()` together.
* Employing library functions like Lodash's `assignIn()` or Moment.js's `assign()`.

While these alternatives might offer similar performance benefits as the `Object.assign()` method, they may also introduce additional overhead due to function calls or require additional libraries.

Related benchmarks:

Object.assign vs direct assignment multiple properties (version: 0)

Comparing performance of: Direct Assignment vs Object.assign

Created: one year ago by: Guest

Jump to the latest result

Direct Assignment

Object.assign

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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