Benchmark: Delete vs Undefined

Script Preparation code:

var obj = {
    property : "value"
};

Tests:

Delete
delete obj.property
Undefined
obj.property = undefined;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Delete
Undefined

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36 Edg/131.0.0.0

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
Delete	33054492.0 Ops/sec
Undefined	27099766.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this JavaScript microbenchmark on MeasureThat.net.

**Benchmark Definition**

The benchmark compares two approaches to delete or set a property to undefined on an object:

1. **Delete**: `delete obj.property`
2. **Undefined**: `obj.property = undefined;`

**Options Compared**

We have two options being compared:

* `delete` keyword: This is a built-in JavaScript operator that removes a property from an object by its name.
* Assignment to `undefined`: Setting a property to `undefined` effectively deletes it.

**Pros and Cons of Each Approach**

1. **Delete**
	* Pros:
		+ More concise and readable syntax.
		+ Often perceived as more efficient since it doesn't create a temporary variable.
	* Cons:
		+ Can be slower due to the dynamic nature of JavaScript's property removal process.
		+ May not work consistently across all browsers and environments.
2. **Undefined**
	* Pros:
		+ More explicit and predictable behavior.
		+ Works consistently across all browsers and environments.
	* Cons:
		+ Requires an additional assignment statement, which can be less concise.

**Other Considerations**

* **Memory Management**: Both approaches may have implications for memory management, as the `delete` keyword only removes a reference to the property from the object's internal hash table, while setting a property to `undefined` actually deallocates the memory allocated by the property.
* **Property Existence Checks**: Depending on use cases, it might be necessary to check if a property exists before attempting to delete or set it to `undefined`. Both approaches can lead to additional checks.

**Library or Special JS Feature Used**

There are no libraries mentioned in this benchmark, and no special JavaScript features (e.g., async/await, generators) are used beyond the standard JavaScript language.

**Alternatives**

Other alternatives for deleting properties from an object include:

* `Object.defineProperty()` with `configurable: false`
* `Object.delete()` (not supported in older browsers)
* Using a temporary variable and assigning it to `null` or `undefined`, followed by property removal

Keep in mind that these alternatives might not offer significant performance benefits over the delete and assignment approaches, and may have different implications for memory management and other factors.

Related benchmarks:

Delete vs Undefined (version: 0)

Compare JavaScript deletion on object vs setting to undefined.

Comparing performance of: Delete vs Undefined

Created: 3 years ago by: Guest

Jump to the latest result

Delete

Undefined

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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