Benchmark: Check existence - MeasureThat.net

Tests:

typeof
typeof window !== 'undefined'
undefined
window !== undefined
void(8)
window !== void(8)
!!
!!window
if
if (window) {}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
undefined
void(8)
!!
if

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Browser/OS: Chrome 53 on Windows

View result in a separate tab

Test name	Executions per second
typeof	3122860.0 Ops/sec
undefined	1867494.4 Ops/sec
void(8)	3204830.2 Ops/sec
!!	3190281.5 Ops/sec
if	3219505.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of what's being tested in this benchmark.

**Overview**

The provided JSON represents a JavaScript microbenchmark that tests various ways to check if the `window` object is defined or not. The test cases use different syntax and techniques to achieve the same goal, which is to verify whether the `window` object exists in the current context.

**Test Cases**

Here's a brief description of each test case:

1. `typeof window !== 'undefined'`: This test case checks if the result of `typeof window` is not equal to `'undefined'`. It's using the `typeof` operator, which returns a string indicating the type of the object.
2. `window !== undefined`: This test case checks if the `window` variable is not equal to `undefined`.
3. `window !== void(8)`: This test case uses the unary `!` operator and the `void()` function to check if `window` is not equal to `void(8)`, which returns `undefined`. The `void()` function essentially creates an empty function, which is then coerced to `undefined`.
4. `!!window`: This test case uses the double-tilde (`!!`) operator to convert the boolean value of `window` (which would be `true` or `false`) to a number (1 for `true` and 0 for `false`). It then checks if this result is truthy or falsy.
5. `if (window) {}`: This test case uses an if-statement with the condition `window`. If the window object exists, the code inside the if-statement will execute.

**Libraries**

None of these test cases rely on any external libraries. They only use built-in JavaScript features and operators to achieve their goals.

**Special JS Features or Syntax**

The following special features or syntax are used in some of the test cases:

* The `typeof` operator (used in test case 1)
* The `void()` function (used in test case 3)
* The double-tilde (`!!`) operator (used in test case 4)

These operators and functions are part of the standard JavaScript language.

**Pros and Cons**

Here's a brief analysis of each test case:

* Test case 1: Using `typeof` is straightforward, but it might be less efficient than other methods since it involves a function call.
	+ Pros: Easy to read and understand
	+ Cons: Might be slower due to the function call
* Test case 2: Directly checking if `window` is not equal to `undefined` is simple and efficient.
	+ Pros: Fast and straightforward
	+ Cons: Might not work in all scenarios (e.g., if `window` is a variable that holds an object)
* Test case 3: Using the `void()` function with the unary `!` operator might seem unusual, but it's a common pattern to check for `undefined`.
	+ Pros: Can be faster than other methods
	+ Cons: Might not be as straightforward to read and understand
* Test case 4: The double-tilde (`!!`) operator is useful when you need to convert a boolean value to a number.
	+ Pros: Useful in certain scenarios
	+ Cons: Not as well-known or widely used as other methods
* Test case 5: Using an if-statement with the condition `window` is a more traditional way to check for its existence.
	+ Pros: Easy to read and understand
	+ Cons: Might be slower than other methods due to the branching

**Alternatives**

If you wanted to test these conditions in different ways, here are some alternative approaches:

* Use `!!window === true` instead of `!!window`
* Use the `Object.is()` method instead of comparing values directly (e.g., `window !== undefined`)
* Use a regex pattern to check if `window` exists (e.g., `/^window$/.test(window)`)

Keep in mind that these alternatives might not be as efficient or readable, and it's essential to consider the specific requirements and constraints of your project when choosing an approach.

Related benchmarks:

Check existence (version: 2)

Comparing performance of: typeof vs undefined vs void(8) vs !! vs if

Created: 8 years ago by: Registered User

Jump to the latest result

typeof

undefined

void(8)

!!

if

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):