Benchmark: delete vs assign to null

Tests:

Delete
const master = { foo: 'bah', bah: 'foo', lorem: 'lorem' } const second = { ...master }; delete second.foo;
Assign to undefined
const master = { foo: 'bah', bah: 'foo', lorem: 'lorem' } const result = { ...master, foo: undefined };
Assign to null
const master = { foo: 'bah', bah: 'foo', lorem: 'lorem' } const result = { ...master, foo: null };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Delete
Assign to undefined
Assign to null

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Overview**

The provided JSON represents a benchmark that tests the performance difference between three approaches:

1.  `delete obj.key`
2.  Assigning a value to an undefined property: `obj.key = undefined`
3.  Assigning a null value to a key: `obj.key = null`

These approaches aim to measure which method is faster for deleting or setting properties in JavaScript objects.

**Options Comparison**

1.  **delete obj.key**: This approach directly deletes the specified property from the object. It's concise and efficient.
2.  **Assigning to undefined**: By assigning a value to an undefined property, you're essentially "deleting" it. However, this method is less efficient due to the need for a property lookup in the object.
3.  **Assigning to null**: Similar to assigning to undefined, but with a different data type.

**Pros and Cons**

*   `delete obj.key`:
    *   Pros: Fastest execution time since it directly deletes the property without any intermediate lookups.
    *   Cons: May not be suitable for use cases where you need to retain the object's structure or keep track of deleted properties.
*   Assigning to undefined (`obj.key = undefined`):
    *   Pros: Can be used when you want to preserve the object's original structure and still "delete" a property.
    *   Cons: Less efficient due to the additional lookup step required in the object.
*   Assigning to null (`obj.key = null`):
    *   Pros: Can provide better performance than assigning to undefined, but may not be as straightforward to use.
    *   Cons: This approach can lead to unexpected behavior if you're not careful with property names.

**Library Usage**

There is no specific library mentioned in the provided JSON. However, it's worth noting that some libraries like Lodash provide utility functions for working with objects, such as `unset` or `deleteProperty`, which might be used in real-world scenarios.

**Special JavaScript Features/Syntax**

None of the provided benchmark definitions use any special JavaScript features or syntax. The examples focus solely on basic object property manipulation using standard JavaScript operators and syntax.

**Alternatives**

If you're interested in exploring alternative approaches, here are a few:

*   Using `Object.keys()` and `forEach()` to iterate over properties and delete them individually: `Object.keys(master).forEach((key) => delete master[key]);`
*   Utilizing modern JavaScript features like `Object.fromEntries()` and `entries()` to manipulate objects: `const result = Object.fromEntries(Object.entries(master).map(([key, value]) => [key, null]));`

Keep in mind that these alternatives might not be as efficient as the original approaches, but they demonstrate other ways to approach object property manipulation.

I hope this explanation helps you understand the nuances of JavaScript microbenchmarks!

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/113.0.0.0 Safari/537.36

Browser/OS: Chrome 113 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Delete	10316582.0 Ops/sec
Assign to undefined	14888206.0 Ops/sec
Assign to null	107539952.0 Ops/sec

Related benchmarks:

delete vs assign to null (version: 1)

The idea's to know the time difference between using "delete obj.key" rather than obj.key = null.

Comparing performance of: Delete vs Assign to undefined vs Assign to null

Created: 6 years ago by: Registered User

Jump to the latest result

Delete

Assign to undefined

Assign to null

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):