Benchmark: Object.defineProperty vs direct assignment (ES6, minimal GC)

Script Preparation code:

const val_obj = {
    value: null,
    configurable: true,
    enumerable: true,
    writable: true
};

function val(value) {
    val_obj.value = value;
    return val_obj;
}

Tests:

defineProperty
let key = 'something'; const target = {}; for (let i=0; i<1000; i++) Object.defineProperty(target, i, val(key+i));
direct assign
let key = 'something'; const target = {}; for (var i=0; i<1000; i++) target[i] = key+i;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
defineProperty
direct assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36

Browser/OS: Chrome 141 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
defineProperty	14738.7 Ops/sec
direct assign	74513.6 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 and analyze the provided benchmark.

**Benchmark Definition**

The benchmark is defined in two parts:

1. **Script Preparation Code**: This code sets up a test object `val_obj` with properties `value`, `configurable`, `enumerable`, and `writable`. It also defines a function `val` that takes a value as an argument, assigns it to the `value` property of `val_obj`, and returns `val_obj`.
2. **Html Preparation Code**: This field is empty in the provided benchmark definition, which means no HTML preparation code is needed.

**Options Being Compared**

The benchmark compares two approaches:

1. **`Object.defineProperty(target, i, val(key+i))`**: This approach uses `Object.defineProperty` to define a property on the target object `target`. The property is created dynamically using the function `val`.
2. **`target[i] = key+i`**: This approach assigns a value to the `i-th` property of the target object `target` directly.

**Pros and Cons of Each Approach**

1. **`Object.defineProperty(target, i, val(key+i))`**:
	* Pros:
		+ Provides more control over the property definition (e.g., setting its name, getter, setter).
		+ May be more efficient for large objects with many properties.
	* Cons:
		+ Can be slower due to the overhead of calling `Object.defineProperty`.
2. **`target[i] = key+i`**:
	* Pros:
		+ Faster since it avoids the overhead of calling `Object.defineProperty`.
	* Cons:
		+ Less control over property definition (e.g., no getter or setter).
		+ May lead to issues with property access patterns, especially when dealing with large objects.

**Library and Special JS Features**

The benchmark uses the built-in JavaScript `Object` and `Array` types. There are no external libraries used in this benchmark.

**Special JS Feature/Syntax**

There is a notable aspect of this benchmark: the use of `var` instead of `let` or `const` for declaring the variable `i`. In modern JavaScript, it's recommended to use `let` or `const` instead of `var` due to its scoping behavior.

**Other Alternatives**

If you wanted to explore alternative approaches, here are a few options:

1. **Using `Array.prototype.at()`**: Instead of using `Object.defineProperty`, you could use the new `at()` method introduced in ECMAScript 2022 to access properties on objects.
```javascript
const target = {};
for (let i=0; i<1000; i++) {
  target.at(i) = val(key+i);
}
```
This approach avoids the need for `Object.defineProperty` but may have its own performance implications.

2. **Using a library like Lodash's `_defineProperty()`**: If you prefer a more explicit and controlled approach, you could use a utility function from a library like Lodash to define properties on objects.
```javascript
const _ = require('lodash');
const target = {};
for (let i=0; i<1000; i++) {
  _.defineProperty(target, i, val(key+i));
}
```
This approach adds some overhead due to the need to include an external library but provides more control over property definition.

Keep in mind that these alternatives may have different performance characteristics and trade-offs compared to the original benchmark.

Related benchmarks:

Object.defineProperty vs direct assignment (ES6, minimal GC) (version: 0)

Comparing performance of: defineProperty vs direct assign

Created: 2 years ago by: Guest

Jump to the latest result

defineProperty

direct assign

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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