Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty vs. Void 0

Script Preparation code:

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

Tests:

undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;
Void
void 0 !== obj.d;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
bool
Void

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36

Browser/OS: Chrome 99 on Windows 7

View result in a separate tab

Test name	Executions per second
undefined	3212059.8 Ops/sec
typeof	8602970.0 Ops/sec
in	8658614.0 Ops/sec
hasOwnProperty	7819593.0 Ops/sec
bool	8459865.0 Ops/sec
Void	8645230.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition**

The provided JSON represents a benchmark test case named "undefined vs. typeof vs. in vs. hasOwnProperty vs. Void 0". The description indicates that this benchmark tests object lookup performance.

**Options Compared**

In this benchmark, six different options are compared:

1. `undefined`
2. `typeof` (the `typeof` keyword)
3. `in` (the `in` operator)
4. `hasOwnProperty` (a method of objects)
5. `!!` (the double exclamation mark operator, which converts a value to a boolean)
6. `void 0` (an expression that returns the result of the expression `0`)

**Pros and Cons**

Each option has its own strengths and weaknesses:

* `undefined`: This is the most basic and straightforward way to test if a property exists in an object. However, it may not be the fastest or most efficient way.
* `typeof`: The `typeof` operator checks the type of a variable. In this case, it can be used to check if `obj.d` is a defined property. However, it may not be as fast as other options because it performs an additional operation.
* `in`: The `in` operator checks if a property exists in an object. It is generally faster than the `typeof` operator but may not work correctly for some types of objects.
* `hasOwnProperty`: This method checks if an object has a specific property, and it is generally more efficient than using the `in` operator or `typeof`.
* `!!`: The double exclamation mark operator converts a value to a boolean. In this case, it can be used to test if `obj.d` exists in a more concise way.
* `void 0`: This expression returns the result of evaluating `0`, which is equivalent to `undefined`. It is often used as a shorthand for checking if a property exists.

**Library**

There is no explicit library mentioned in the benchmark definition. However, the `hasOwnProperty` method is a part of the Object prototype, which is an object that provides methods and properties common to all objects.

**Special JS Features/Syntax**

None of the options use special JavaScript features or syntax that are not widely supported. The benchmark focuses on testing basic object lookup performance using standard operators and methods.

**Other Alternatives**

If you want to test object lookup performance, there are other alternatives:

* Using the `Object.prototype.hasOwnProperty()` method instead of `hasOwnProperty`
* Using the `in` operator with a different property or object
* Using the `typeof` operator with a different type or expression
* Testing with arrays or other types of objects

It's worth noting that these alternatives may not be as efficient or accurate as the original options, and the results may vary depending on the specific use case and environment.

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty vs. Void 0 (version: 0)

Object lookup performance

Comparing performance of: undefined vs typeof vs in vs hasOwnProperty vs bool vs Void

Created: 3 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwnProperty

bool

Void

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):