Benchmark: delete vs undefined

Tests:

undefined
var obj = {}; for(var i = 0; i < 1000;i++) { obj[`a${i}`] = i; } for(var i = 0; i < 1000;i++) { obj[`a${i}`] = undefined; }
delete
var obj = {}; for(var i = 0; i < 1000;i++) { obj[`a${i}`] = i; } for(var i = 0; i < 1000;i++) { delete obj[`a${i}`]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
delete

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its options.

**What is being tested?**

The benchmark measures the performance difference between two approaches: using `delete` to remove properties from an object, versus using `undefined` as a value for those properties.

In other words, the test creates a large object with 1000 properties (using a loop), then attempts to set each of these properties to either `undefined` or delete them. The goal is to determine which approach is faster.

**Options being compared**

There are two main options:

1. **Using `delete`**: This approach explicitly removes the property from the object, using the `delete` keyword.
2. **Using `undefined`**: This approach sets the property's value to `undefined`, effectively removing it from the object.

**Pros and Cons of each approach**

**Using `delete`**:

Pros:

* Clearly communicates intention to remove a property
* Can be useful for debugging or logging purposes

Cons:

* May have performance implications due to the overhead of deleting properties
* Can lead to unexpected behavior if used in certain contexts (e.g., when using `Object.assign()`)

**Using `undefined`**:

Pros:

* Faster and more lightweight than using `delete`
* Often preferred for its concise syntax

Cons:

* May not be as clearly readable or maintainable, especially for complex codebases
* Can lead to confusing behavior if not used carefully (e.g., when iterating over properties)

**Library: None**

There are no external libraries being tested in this benchmark.

**Special JavaScript features/syntax**

This benchmark does not use any special JavaScript features or syntax beyond what is considered standard. However, it's worth noting that modern browsers may optimize certain operations using techniques like just-in-time (JIT) compilation or caching. But for the purposes of this explanation, we'll assume a basic JavaScript runtime environment.

**Other alternatives**

If you're interested in alternative approaches to removing properties from objects, consider:

1. **Using `Object.keys()` and `forEach()`**: Loop through each property name, delete it, and then reassign the object.
2. **Using `Object.defineProperties()` and `deleteProperty()`**: Define a new property with an empty value, then immediately delete it.
3. **Using `Object.assign()` with an empty object**: Create a new object with no properties, then assign it to the original object.

Keep in mind that these alternatives may have different performance characteristics or use cases compared to using `delete` and setting properties to `undefined`.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.61 Safari/537.36

Browser/OS: Chrome 102 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
undefined	4813.0 Ops/sec
delete	7376.6 Ops/sec

Related benchmarks:

delete vs undefined (version: 0)

Comparing performance of: undefined vs delete

Created: 4 years ago by: Guest

Jump to the latest result

undefined

delete

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):