Benchmark: Array length assertion

Script Preparation code:

var arrArr = [[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3],[], [], [1,2,3]];

Tests:

!!arr.length
for (arr in arrArr) { if (!!arr.length) console.log(1) else console.log(0) }
arr.length > 0
for (arr in arrArr) { 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
!!arr.length
arr.length > 0

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
!!arr.length	11082.7 Ops/sec
arr.length > 0	10785.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is a complex task, and the provided benchmark definition and test cases provide valuable insights into the different approaches used.

**Benchmark Definition:**
The benchmark definition specifies two scripts to be executed repeatedly in a loop, which will measure the performance of two specific expressions:

1. `!!arr.length` (double negation operator)
2. `arr.length > 0`

These expressions are evaluated for each array in the `arrArr` array.

**Script Preparation Code:**
The script preparation code creates the `arrArr` array, which contains multiple arrays of varying lengths, including empty arrays. This array is used as input for the two expressions being measured.

**Html Preparation Code:**
There is no HTML preparation code specified, which means that the benchmarking process does not involve any HTML-related overhead or dependencies.

**Options Compared:**

1. `!!arr.length`: This option uses the double negation operator to check if the array length is truthy (i.e., non-zero).
	* Pros: Simple and concise expression.
	* Cons: May be slower due to the double negation operation.
2. `arr.length > 0`: This option checks if the array length is greater than zero.
	* Pros: More readable and intuitive expression, potentially faster execution.
	* Cons: The comparison operator may introduce additional overhead.

**Other Considerations:**

1. **Array Length Caching:** Some JavaScript engines (like V8) cache the result of `arr.length` after the first evaluation. This means that subsequent evaluations will be faster, but only if the array length hasn't changed.
2. **Null and Undefined Values:** The benchmark does not account for null or undefined values in the arrays. In a real-world scenario, these would need to be handled differently.

**Library/Functionality Used:**
There is no explicit library mentioned, but the use of `!!` (double negation operator) is a built-in JavaScript feature. However, if we were to consider external libraries or functions, some common alternatives for similar checks could include:

* Using `Boolean(arr.length)` (not as concise as `!!arr.length`)
* Utilizing `Array.prototype.some()` with a callback function
* Employing `Math.max()` and comparing the result to 0

**Special JS Features/Syntax:**
There is no special JavaScript feature or syntax explicitly used in this benchmark, apart from the use of `!!` which is a built-in operator.

**Other Alternatives:**

1. **Alternative Implementations:** If we were to rewrite these expressions using different approaches (e.g., bit manipulation or arithmetic operations), we might achieve better performance.
2. **Profiling:** To further optimize performance, additional profiling techniques could be employed, such as analyzing the call stack, function arguments, and variable scopes.

In summary, this benchmark provides a good starting point for understanding the performance of different JavaScript expressions in various contexts. By considering factors like array length caching, null/undefined values, and alternative implementations, we can gain deeper insights into optimizing JavaScript performance.

Related benchmarks:

Array length assertion (version: 0)

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

Created: 2 years ago by: Guest

Jump to the latest result

!!arr.length

arr.length > 0

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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