Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty 25

Script Preparation code:

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

Tests:

undefined
if(undefined !== obj.d){}
typeof
if('undefined' !== typeof obj.d){}
in
if('d' in obj){}
hasOwnProperty
if(obj.hasOwnProperty( 'd' )){}
bool
if(!!obj.d){}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
bool

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 dive into the world of JavaScript microbenchmarks!

**Benchmark Definition JSON**

The provided JSON represents a benchmark test case that measures the performance of different methods for checking if a variable exists in an object.

* `Name`: The name of the benchmark, which is "undefined vs. typeof vs. in vs. hasOwnProperty 25".
* `Description`: A brief description of the benchmark, which is "Object lookup performance".
* `Script Preparation Code` and `Html Preparation Code`: These are code snippets that are executed before running each test case. The script preparation code defines an object `obj` with five properties: `a`, `b`, `c`, `d`, and `e`.

**Individual Test Cases**

There are six test cases, each representing a different method for checking if a variable exists in the `obj` object:

1. `undefined`: Checks if `obj.d` is not equal to `undefined`.
2. `typeof`: Checks if `typeof obj.d` is not equal to `'undefined'`.
3. `in`: Checks if `'d'` is present as a property in `obj`.
4. `hasOwnProperty`: Checks if `obj.hasOwnProperty('d')` is true.
5. `bool`: A custom test case that checks if the value of `obj.d` is truthy (i.e., not null, undefined, or false).

**Performance Comparison**

The benchmark measures the performance of each test case by executing it multiple times and calculating the average execution time per second.

* The results show that:
	+ `bool` has the highest performance, with an average execution time of 3391172.25 executions per second.
	+ `in` has a relatively high performance, with an average execution time of 8280187.0 executions per second.
	+ `typeof` and `hasOwnProperty` have similar performances, with average execution times of around 9000018.0 and 9356926.0 executions per second, respectively.
	+ The `undefined` test case has the lowest performance, with an average execution time of 9376568.0 executions per second.

**Pros and Cons**

Here are some pros and cons for each approach:

* `bool`: This method is likely to be the fastest since it simply checks if the value is truthy, without any unnecessary object traversal.
	+ Pros: Simple, fast, and easy to implement.
	+ Cons: May not work as expected for certain types of values (e.g., NaN or undefined).
* `in`: This method uses the `in` operator to check if a property exists in an object. It's relatively fast but may be slower than `bool`.
	+ Pros: Fast, reliable, and works well with most types of objects.
	+ Cons: May be slower than `bool`, depending on the JavaScript engine used.
* `typeof`: This method uses the `typeof` operator to check if a value is an object. It's generally slow since it involves type checking.
	+ Pros: Can work with various data types, but may be slower due to type checking overhead.
	+ Cons: May be slower than other methods, especially for objects or arrays.
* `hasOwnProperty`: This method uses the `hasOwnProperty` method of an object to check if a property exists in the same object. It's relatively slow since it involves a method call.
	+ Pros: Works well with objects, but may be slower due to method call overhead.
	+ Cons: May be slower than other methods, especially for large arrays or objects.

**Other Considerations**

* **Library usage**: The benchmark uses no external libraries beyond the standard JavaScript Object model (e.g., `in` and `hasOwnProperty`).
* **Special JS features**: No special JavaScript features or syntax are used in this benchmark.

**Alternatives**

If you want to create your own microbenchmarking test cases, here are some alternatives:

1. Use a library like Benchmark.js, which provides a simple API for creating and running benchmarks.
2. Create custom tests using Node.js's built-in `performance` module or the V8 JavaScript Engine's built-in benchmarking tools (for server-side development).
3. Utilize existing open-source benchmarking libraries like js-benchmark or microbenchmark.

Keep in mind that different browsers, engines, and hardware can affect performance results, so it's essential to run benchmarks on multiple platforms and with various configurations to ensure accurate comparisons.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36

Browser/OS: Chrome 78 on Windows

View result in a separate tab

Test name	Executions per second
undefined	3391172.2 Ops/sec
typeof	9000018.0 Ops/sec
in	9356926.0 Ops/sec
hasOwnProperty	8280187.0 Ops/sec
bool	9376568.0 Ops/sec

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty 25 (version: 0)

Object lookup performance

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

Created: 4 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwnProperty

bool

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):