Benchmark: undefined vs hasOwnProperty

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

Tests:

undefined
undefined !== obj['d'];
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
hasOwnProperty
bool

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:100.0) Gecko/20100101 Firefox/100.0

Browser/OS: Firefox 100 on Linux

View result in a separate tab

Test name	Executions per second
undefined	938930752.0 Ops/sec
hasOwnProperty	988273152.0 Ops/sec
bool	983348608.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**
The benchmark is defined as an object with four properties: `Name`, `Description`, `Script Preparation Code`, and `Html Preparation Code`. In this case, the description is "Object lookup performance".

**Options Compared**
The script preparation code defines three different ways to look up a property in an object:

1. Using the `undefined` keyword: `var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 }; undefined !== obj['d'];`
2. Using the `hasOwnProperty()` method: `obj.hasOwnProperty('d');`
3. Using the double exclamation mark (`!!`) operator: `!! obj.d;`

The description suggests that these three approaches are being compared in terms of performance.

**Pros and Cons**

* **Using `undefined`**: This approach is simple and straightforward. However, it may not be as efficient as other methods, as the JavaScript engine needs to perform a property lookup on the `obj` object.
* **Using `hasOwnProperty()`**: This method is more efficient than using `undefined`, as it uses a native method that is optimized by the browser's engine. It also provides additional information about whether the property exists or not.
* **Using `!!` operator**: The double exclamation mark operator performs a type coercion and returns a boolean value. While this may seem like an unusual approach, it can be faster than using `hasOwnProperty()` for some use cases.

**Library**
None of the provided benchmark definitions rely on external libraries. However, the benchmark uses the `!!` operator, which is a part of the JavaScript language standard.

**Special JS Features/Syntax**
There are no special JavaScript features or syntax used in this benchmark. The code snippets are straightforward and easy to understand.

**Other Alternatives**

* To compare the performance of different object lookup methods, you could also use other approaches, such as:
	+ Using `in` operator: `var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 }; 'd' in obj;`
	+ Using the `typeof` operator with the `object` type: `var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 }; typeof obj['d'] === 'object';`
	+ Using a closure to create a function that checks if a property exists on an object.

Keep in mind that these alternatives may introduce additional overhead or complexity compared to the original approach.

Related benchmarks:

undefined vs hasOwnProperty (version: 0)

Object lookup performance

Comparing performance of: undefined vs hasOwnProperty vs bool

Created: 4 years ago by: Guest

Jump to the latest result

undefined

hasOwnProperty

bool

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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