Benchmark: Delete undefined property

Script Preparation code:

var obj = {}

Tests:

Delete undefined property
delete obj.prop
Avoid delete undefined property
if (!('prop' in obj)) { delete obj.prop }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Delete undefined property
Avoid delete undefined property

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is defined by two JavaScript code snippets: `delete obj.prop` and `if (!('prop' in obj)) { delete obj.prop; }`. These two codes are designed to test how browsers handle deleting properties from an object when that property doesn't exist.

**What's being tested?**

In the first case, `delete obj.prop`, the code directly deletes a non-existent property (`obj.prop`). This is intended to measure how browsers optimize or handle such operations. In contrast, the second case uses a conditional statement (`if (!('prop' in obj))`) before deleting the property. This adds an extra step that checks if the property exists before attempting to delete it.

**Options compared**

The two options being compared are:

1. **Direct deletion**: `delete obj.prop` (first benchmark definition). This approach directly attempts to delete a non-existent property, which can lead to errors and potentially slow down the browser.
2. **Conditional check**: `if (!('prop' in obj)) { delete obj.prop; }` (second benchmark definition). This approach checks if the property exists before deleting it, avoiding potential errors and potentially improving performance.

**Pros and Cons**

* Direct deletion (`delete obj.prop`):
	+ Pros: Simple, straightforward code.
	+ Cons: May lead to errors or slow down the browser due to undefined behavior.
* Conditional check (`if (!('prop' in obj)) { delete obj.prop; }`):
	+ Pros: Reduces the risk of errors and potentially improves performance by avoiding undefined behavior.
	+ Cons: Adds an extra step, which might incur a small overhead.

**Library usage**

There is no apparent library being used in this benchmark. The code snippets are simple and standalone JavaScript expressions.

**Special JS feature or syntax**

There's no special JavaScript feature or syntax being tested in this benchmark. It's a straightforward test of how browsers handle deleting properties from an object when that property doesn't exist.

**Other alternatives**

To measure similar performance characteristics, you could create additional benchmark definitions using other approaches, such as:

* Using `in` operator: `for (var i = 0; i < 10000; i++) { if ('prop' in obj) { delete obj.prop; } }`
* Using a try-catch block to handle errors: `try { delete obj.prop; } catch (e) { /* ignore error */ }`

These alternatives would test how browsers optimize or handle errors when attempting to delete non-existent properties.

I hope this explanation helps you understand the benchmark and what's being tested!

Related benchmarks:

Delete undefined property (version: 0)

Comparing performance of: Delete undefined property vs Avoid delete undefined property

Created: 4 years ago by: Registered User

Jump to the latest result

Delete undefined property

Avoid delete undefined property

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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