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

Script Preparation code:

var arr = [];

Tests:

!!array.length
if (!!arr.length) { console.log(1); } else { console.log(0); }
array.length > 0
if (arr.length > 0) { console.log(1); } else { console.log(0); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36

Browser/OS: Chrome 132 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
!!array.length	808309.9 Ops/sec
array.length > 0	806348.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and discussed.

**Benchmark Overview**

The test measures the performance difference between two approaches to check if an array is not empty:

1. `!!array.length` (also known as the "doublebang" trick)
2. `arr.length > 0`

**Options Compared**

Two options are being compared in this benchmark:

a. `!!array.length`: This approach uses a double exclamation mark (!!) to force JavaScript to evaluate the expression as a boolean value, even if it's not explicitly marked as such (like `if` statements). This is done to avoid issues with some older browsers that might interpret the expression differently.

b. `arr.length > 0`: This approach directly checks if the array length is greater than 0 using the comparison operator.

**Pros and Cons**

a. `!!array.length`:
   Pros: 
     - Can work around potential issues in older browsers.
     - Often used in practice for concise code.
   Cons: 
     - Less intuitive to read, as it's not immediately clear what it does without knowing the doublebang trick.
     - May lead to confusion when debugging.

b. `arr.length > 0`:
   Pros: 
     - More straightforward and easy to understand for most readers.
     - Avoids potential browser issues by using a standard comparison operator.
   Cons: 
     - May require explicit type checking (in older browsers), which can be slower.

**Library and Special JS Feature**

In the test case, `Yowser` is mentioned in the `RawUAString`. Yowser is a feature that allows modern web pages to look like they were designed for mobile devices on desktop computers. It does this by rendering mobile versions of websites as if they were viewed on a mobile device. This feature doesn't affect the performance test itself.

**Other Considerations**

The benchmark preparation code creates an empty array (`var arr = [];`) and defines no variables or functions outside of these lines. The HTML preparation code is null, indicating that no additional setup for the test environment is required beyond what's defined in JavaScript.

For users without deep knowledge of JavaScript:

- Be aware that `!!array.length` works by converting a value to a boolean using its truthiness rules.
- Understand that comparing `arr.length > 0` directly checks if there are elements in the array, which might be faster on average but relies on explicit type checking.

For software engineers who may have worked with JavaScript extensively:

- Familiarize yourself with potential quirks and edge cases related to boolean coercion and doublebang tricks.
- Consider performance implications when choosing between direct comparison (`arr.length > 0`) and indirect methods like `!!array.length`.

Related benchmarks:

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

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

Created: one year ago by: Guest

Jump to the latest result

!!array.length

array.length > 0

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):