Benchmark: typeof number vs not typeof undefined vs undefined

Script Preparation code:

var something = 4;

Tests:

typeof number
typeof something === "number";
!= typeof undefined
typeof something !== "undefined";
!= undefined
something !== undefined;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof number
!= typeof undefined
!= undefined

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

Browser/OS: Chrome 120 on Windows

View result in a separate tab

!= typeof undefined

21.6M/s

typeof number

21.5M/s

!= undefined

9.2M/s

View exact numbers

Test name	Executions per second
✓ != typeof undefined	21,642,574 Ops/sec
typeof number	21,491,080 Ops/sec
!= undefined	9,241,059 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and the pros/cons of different approaches.

**Benchmark Overview**

The benchmark is designed to test the performance difference between three types of comparisons:

1. `typeof number`
2. `!= typeof undefined`
3. `!= undefined`

These comparisons are used to check if a variable (`something`) has a type that can be coerced to "number" (i.e., it's a number) or if it's not equal to `undefined`.

**Script Preparation Code**

The script preparation code is `var something = 4;`, which sets a constant variable `something` to the value 4. This ensures that each test case has access to the same variable, eliminating any variability due to different initialization.

**Html Preparation Code**

There is no HTML preparation code provided, so we'll assume that the benchmark is run in a headless browser environment or uses a custom test harness.

**Comparison Approaches**

Now, let's discuss the pros and cons of each comparison approach:

1. `typeof number`
	* Pros: Fast and efficient way to check if a variable has a type that can be coerced to "number".
	* Cons: May not work correctly for certain edge cases (e.g., NaN, Infinity).
2. `!= typeof undefined`
	* Pros: Simple and straightforward way to check if a variable is not equal to `undefined`.
	* Cons: May be slower than the first approach due to the need to perform a type coercion.
3. `!= undefined`
	* Pros: Similar to the second approach but avoids the type coercion overhead by directly checking for equality with `undefined`.
	* Cons: Less readable and less intuitive compared to the second approach.

**Library Usage**

There is no library usage mentioned in the benchmark definition or test cases. However, if a library was used, it would likely be a JavaScript standard library function, such as `Number()` or `IsNaN()`, to perform type checks.

**Special JS Features/Syntax**

None are explicitly mentioned, but we should note that this benchmark does not use any special features like async/await, Promises, or destructuring, which might affect the performance of certain browsers.

**Other Alternatives**

If you were to rewrite this benchmark with alternative approaches, some options could be:

* Using a binary search approach to compare the values instead of using direct comparisons.
* Measuring the performance of different type systems (e.g., strict vs. loose type checking) or compiler optimizations (e.g., inline functions).
* Adding more test cases to cover additional scenarios, such as:
	+ `typeof NaN`
	+ `typeof Infinity`
	+ Comparison with other types (e.g., string, boolean)
	+ Comparing objects or arrays instead of primitive values

These alternatives would likely require significant changes to the benchmark setup and implementation but could provide valuable insights into performance optimization strategies.

typeof number vs not typeof undefined vs undefined (version: 0)

Comparing performance of: `typeof number vs != typeof undefined vs != undefined`

Created: 2 years ago by: Guest

Go to the latest result

typeof number

!= typeof undefined

!= undefined

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

typeof number vs not typeof undefined vs undefined (version: 0)

Comparing performance of: typeof number vs != typeof undefined vs != undefined

Created: 2 years ago by: Guest

Go to the latest result

typeof number

!= typeof undefined

!= undefined

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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Comparing performance of: `typeof number vs != typeof undefined vs != undefined`