Benchmark: array.length === 0 vs !!array.length vs array.length

Tests:

array.length === 0
const array = []; for (let i = 0; i < 10000; i++) { if (array.length === 0) { // } }
!!array.length
const array = []; for (let i = 0; i < 10000; i++) { if (!!array.length) { // } }
array.length
const array = []; for (let i = 0; i < 10000; i++) { if (array.length) { // } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array.length === 0
!!array.length
array.length

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON benchmark and explain what it tests, comparing different approaches, their pros and cons, and other considerations.

**Benchmark Definition**

The test measures the performance of three different ways to check if an array is empty:

1. `array.length === 0`
2. `!!array.length` (using a double negation)
3. `array.length`

These checks are commonly used in JavaScript code, but their performance can vary depending on the browser and engine.

**Test Case Descriptions**

Here's a brief explanation of each test case:

1. `array.length === 0`
This check uses the equality operator (`===`) to compare the array length with 0. If the length is 0, the expression evaluates to true.
2. `!!array.length` (using double negation)
This check uses the double negation operator (`!!`) to invert the boolean value of `array.length`. In most browsers, `!!` converts numbers to booleans: `0` becomes `false`, and any non-zero number becomes `true`. So, this expression effectively checks if `array.length` is not 0.
3. `array.length`
This check simply returns the length of the array as a numeric value.

**Library Use**

There is no library used in these benchmark tests. The tests are focused on measuring the performance of basic JavaScript operators and constructs.

**Special JS Features/Syntax**

None of the test cases use special JavaScript features or syntax that would require additional explanations.

**Performance Comparison**

The three approaches have different performance characteristics:

1. `array.length === 0`: This check is likely to be the slowest, as it involves a comparison operation.
2. `!!array.length`: Using double negation can be faster than comparing with `===`, as it's optimized for performance in most browsers.
3. `array.length`: This approach is likely to be the fastest, as it returns a numeric value without any comparison or inversion operations.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

1. `array.length === 0`:
	* Pros: Clear and explicit code.
	* Cons: May be slower due to comparison operation.
2. `!!array.length` (using double negation):
	* Pros: Can be faster in some browsers.
	* Cons: May not be immediately clear to other developers, as it's a less common idiom.
3. `array.length`:
	* Pros: Fastest approach, likely to be the most efficient.
	* Cons: Returns a numeric value, which might require additional processing.

**Other Alternatives**

If you want to test alternative approaches, consider adding more test cases, such as:

* Using `in` operator (`"0" in array`)
* Comparing with 0 using `===` or `==`
* Checking if the array is empty using a regular expression
* Using a library like Lodash's `isEmpty()` function

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36

Browser/OS: Chrome 119 on Windows

View result in a separate tab

Test name	Executions per second
array.length === 0	142212.9 Ops/sec
!!array.length	134164.1 Ops/sec
array.length	133942.5 Ops/sec

Related benchmarks:

array.length === 0 vs !!array.length vs array.length (version: 0)

Comparing performance of: array.length === 0 vs !!array.length vs array.length

Created: one year ago by: Guest

Jump to the latest result

array.length === 0

!!array.length

array.length

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):