Benchmark: 'value === undefined' VS 'typeof value === "undefined"' when value is defined

Script Preparation code:

var value = "hello";

Tests:

value === undefined
value === undefined
typeof value === "undefined"
typeof value === "undefined"

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
value === undefined
typeof value === "undefined"

Fastest: N/A

Slowest: N/A

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/84.0.4147.125 Safari/537.36

Browser/OS: Chrome 84 on Windows

View result in a separate tab

Test name	Executions per second
value === undefined	4209412.0 Ops/sec
typeof value === "undefined"	12913705.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain what's being tested in the provided benchmark.

**Benchmark Definition**

The benchmark measures the performance difference between two JavaScript operators: `value === undefined` and `typeof value === "undefined"` when `value` is defined (i.e., not null or undefined).

**Options Compared**

Two options are being compared:

1. `value === undefined`: This operator checks if `value` is equal to the primitive value `undefined`. It's a simple and straightforward way to check for this condition.
2. `typeof value === "undefined"`: This operator checks if the type of `value` is "undefined". However, since `value` is already defined (i.e., not null or undefined), its type will always be `"object"`, not `"undefined"`.

**Pros and Cons**

* `value === undefined`:
	+ Pros: Simple and straightforward to understand.
	+ Cons: May be slower due to the additional comparison operation.
* `typeof value === "undefined"`:
	+ Pros: Can take advantage of type inference and caching by the JavaScript engine.
	+ Cons: Less intuitive and may require more cognitive load to understand.

**Library**

There doesn't appear to be a specific library used in this benchmark. The code is straightforward JavaScript, relying on the built-in `===` and `typeof` operators.

**Special JS Feature or Syntax**

There's no special JavaScript feature or syntax being tested in this benchmark. Both options rely on standard language features.

**Other Alternatives**

If you were to reimplement this benchmark, other alternatives could include:

* Using a more sophisticated type system, such as TypeScript.
* Incorporating type inference and caching using libraries like ES modules or Babel plugins.
* Utilizing specialized JavaScript engines, such as V8's `CheckTypedArray` or SpiderMonkey's `TypeOf`

Keep in mind that these alternatives might not directly impact the performance difference between the two options being tested.

Overall, this benchmark provides a simple yet informative insight into the performance characteristics of two commonly used JavaScript operators.

Related benchmarks:

'value === undefined' VS 'typeof value === "undefined"' when value is defined (version: 0)

Comparing performance of: value === undefined vs typeof value === "undefined"

Created: 4 years ago by: Guest

Jump to the latest result

value === undefined

typeof value === "undefined"

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):