Benchmark: defineProperty vs assign vs set

Script Preparation code:

var a = [...Array(1000).keys()].map((k) => [String(k), String(k)])

Tests:

defineProperty
var b = {} for (const [k, v] of a) { Object.defineProperty(b, k, {value: v}) }
assign
var c = {} for (const [k, v] of a) { Object.assign(c, { [k]: v }) }
set
var d = {} for (const [k, v] of a) { d[k] = v }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
defineProperty
assign
set

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/114.0.0.0 Safari/537.36 Edg/114.0.1823.67

Browser/OS: Chrome 114 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
defineProperty	3123.2 Ops/sec
assign	827.7 Ops/sec
set	7753.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmarking test, specifically designed to compare the performance of three different approaches: `defineProperty`, `Object.assign()`, and simple assignment (`set`). The benchmark aims to measure which approach is faster when creating an object with 1000 key-value pairs.

**Approaches Compared**

1. **`defineProperty`**: This method defines a property on an object at runtime, allowing for more flexibility in how the object is structured.
2. **`Object.assign()`**: This method copies all enumerable own properties from one or more source objects to a destination object.
3. **Simple Assignment (`set`)**: This approach directly assigns values to object properties using the syntax `obj[key] = value`.

**Pros and Cons of Each Approach**

1. **`defineProperty`**:
	* Pros: More flexible, allows for property metadata (e.g., accessors, validators).
	* Cons: May incur additional overhead due to the property definition process.
2. **`Object.assign()`**:
	* Pros: Convenient, efficient way to copy properties from one object to another.
	* Cons: May not be optimized for objects with many key-value pairs, as it uses a shallow copy.
3. **Simple Assignment (`set`)**
	* Pros: Fast, lightweight, and easy to use.
	* Cons: May lead to overwriting existing properties if not handled carefully.

**Library Usage**

None of the benchmarking test cases explicitly uses any JavaScript libraries. However, `Object.assign()` is a built-in method, while `defineProperty` and simple assignment are intrinsic JavaScript features.

**Special JS Features/Syntax**

No special JavaScript features or syntax are used in this benchmark.

**Benchmark Results**

The latest benchmark results show that:

1. **Simple Assignment (`set`)**: The fastest approach, with an average execution rate of 7753.02392578125 executions per second.
2. **`Object.assign()`**: Slower than simple assignment, with an average execution rate of 3123.199951171875 executions per second.
3. **`defineProperty`**: The slowest approach, with an average execution rate of 827.6898193359375 executions per second.

**Alternatives**

If you're looking for alternative approaches to benchmarking JavaScript performance:

1. **V8 Benchmark Suite**: A widely used benchmarking suite developed by Google that tests various JavaScript engine features.
2. **JavaScript Performance Benchmarks**: A collection of benchmarks from Mozilla, covering topics like garbage collection, parsing, and execution speed.
3. **BenchMarkU**: A microbenchmarking framework specifically designed for testing the performance of small JavaScript code snippets.

These alternatives offer a range of pre-built benchmarks and tools to help you measure and compare the performance of different JavaScript approaches.

Related benchmarks:

defineProperty vs assign vs set (version: 0)

Comparing performance of: defineProperty vs assign vs set

Created: one year ago by: Registered User

Jump to the latest result

defineProperty

assign

set

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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