Benchmark: in vs simple if - MeasureThat.net

Script Preparation code:

var obj = { a: 1 };

Tests:

in
if ('a' in obj){}
simple if
if (obj.a){}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
in
simple if

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0

Browser/OS: Chrome 120 on Windows

View result in a separate tab

Test name	Executions per second
in	16584766.0 Ops/sec
simple if	16632000.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**What is tested?**

The provided benchmark tests two different approaches to check if a property exists in an object:

1. `in` (also known as the "in" operator): checks if a given key exists in the object.
2. Simple `if` statement: checks if the property is present in the object using a traditional `if` statement.

**Options compared**

The benchmark compares two options to check for property existence:

1. `in` operator
2. Traditional `if` statement (`obj.a === undefined ? false : true;`)

**Pros and Cons of each approach:**

1. **`in` operator**:
	* Pros:
		+ More concise and expressive.
		+ Less CPU-intensive, as it only checks if the property is present in the object's prototype chain.
	* Cons:
		+ May not work as expected with some custom objects or prototypes.
		+ Not supported by older browsers (e.g., IE 11).
2. **Traditional `if` statement**:
	* Pros:
		+ More control over the checking process.
		+ Works correctly with all objects, including those with custom prototypes.
	* Cons:
		+ Less concise and more verbose.
		+ Requires an explicit check for `undefined`, which can lead to errors.

**Library usage**

None of the provided benchmark tests use any libraries. However, if you're using a JavaScript framework or library that provides additional functionality, it's essential to consider how it might impact your benchmarking results.

**Special JS features or syntax**

Neither of the provided test cases uses special JavaScript features or syntax (e.g., async/await, classes, generators).

**Other alternatives**

If you want to explore more options for checking property existence in JavaScript, here are a few additional approaches:

* Using `hasOwnProperty()` method: `obj.hasOwnProperty('a')`
* Using `in` operator with a custom function: `function hasProperty(obj, prop) { return obj[prop] !== undefined; }`
* Using a library like Lodash's `_.has()` function

Keep in mind that the choice of approach depends on your specific use case and performance requirements. If you need more control or are working with older browsers, traditional `if` statement might be a better option. For conciseness and performance, the `in` operator is often the way to go.

Related benchmarks:

in vs simple if (version: 0)

Comparing performance of: in vs simple if

Created: 2 years ago by: Guest

Jump to the latest result

in

simple if

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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