Benchmark: if undefined vs falsy

Tests:

undefined
let s = 'string'; if(s !== undefined) { var b = 1; }
false
let s = 'string'; if(s) { var b = 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
false

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmarking setup and explain what's being tested.

**What is being tested?**

The test cases are comparing the performance of two approaches in JavaScript:

1. `if (s !== undefined)`: This approach checks if the variable `s` is not equal to `undefined`. The intention behind this check is likely to ensure that `s` has a value before attempting to use it.
2. `if (s)`: This approach simply checks if the variable `s` has any truthy value, regardless of whether it's defined or not.

**Options compared**

The two approaches are being compared in terms of their performance impact on execution time.

**Pros and Cons of each approach:**

1. **`if (s !== undefined)`**:
	* Pros:
		+ More explicit and safe, as it explicitly checks for `undefined`.
		+ May be preferred when working with variables that might be set to `undefined` due to errors or invalid inputs.
	* Cons:
		+ Can lead to slower performance due to the additional comparison operation.
2. **`if (s)```**:
	* Pros:
		+ Often faster, as it relies on a shorter and more straightforward check.
		+ Can be useful when working with variables that are likely to have a truthy value.
	* Cons:
		+ May lead to errors or unexpected behavior if the variable `s` has an unexpected value (e.g., `null`, `0`, or an empty string).
		+ Less explicit and less safe, as it doesn't explicitly check for `undefined`.

**Special consideration:**

In this benchmark, there's no special JavaScript feature or syntax being tested. The focus is on the performance difference between these two simple conditional checks.

**Library usage:**

There are no external libraries used in this benchmarking setup.

**Other alternatives:**

When working with conditional checks like `if (s !== undefined)`, some developers might also consider using:

* `if (typeof s === 'undefined')`: This approach explicitly checks the type of `s` to verify if it's `undefined`.
* Using a null check library or utility function, such as `is-undefined` in JavaScript: These libraries provide a more explicit and safe way to perform the same check.

In summary, this benchmark tests the performance difference between two common conditional checks in JavaScript: `if (s !== undefined)` and `if (s)`. The choice of approach depends on the specific use case and desired balance between safety, readability, and performance.

Related benchmarks:

if undefined vs falsy (version: 1)

which is faster

Comparing performance of: undefined vs false

Created: 3 years ago by: Registered User

Jump to the latest result

undefined

false

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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