Benchmark: Test if array is empty

Script Preparation code:

var arr = [];
var status;

Tests:

!arr.length
status = !arr;
arr.length === 0
status = arr.length === 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: one year ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_1_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1.1 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 18 on iOS 18.1.1

View result in a separate tab

Test name	Executions per second
!arr.length	16860502.0 Ops/sec
arr.length === 0	16718280.0 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 JSON and explain what is being tested, compared, and considered in this JavaScript microbenchmark.

**Benchmark Overview**

The benchmark measures the performance of checking if an empty array exists using two different approaches: `!arr.length` and `arr.length === 0`.

**Tested Libraries and Features**

There are no specific libraries mentioned in the provided JSON. However, it's worth noting that the `Array.prototype.length` property is a built-in JavaScript feature used to get the length of an array.

**Comparison of Approaches**

The two approaches being compared are:

1. **!arr.length**: This approach uses the logical NOT operator (`!`) to negate the result of accessing the `length` property of the array. The idea behind this approach is that if the array is empty, its `length` property will be 0, and negating it will yield a truthy value (i.e., true). If the array has elements, its `length` property will be a positive number, and negating it will yield a falsy value (i.e., false).

2. **arr.length === 0**: This approach directly compares the length of the array to 0 using the equality operator (`===`). This is a more explicit way of checking if an array is empty.

**Pros and Cons of Each Approach**

1. **!arr.length**:
	* Pros: It's concise and may be faster due to the potential for short-circuit evaluation in some browsers.
	* Cons: The behavior can be counterintuitive, as many developers might expect `!` to invert a value rather than negate its truthiness.

2. **arr.length === 0**:
	* Pros: It's more explicit and easier to understand, especially for those who are not familiar with the nuances of JavaScript's logical operators.
	* Cons: It may be slightly slower due to the need to access the `length` property twice.

**Considerations**

When choosing between these approaches, consider your specific use case and performance requirements. If you want a concise and potentially faster solution, `!arr.length` might be suitable. However, if you prioritize code readability and understanding, `arr.length === 0` is likely a better choice.

**Other Alternatives**

If you're looking for alternative ways to check if an array is empty in JavaScript, consider the following:

* Using `Boolean(arr)`: This approach converts the array to a boolean value, which will be falsey (i.e., zero, null, undefined, NaN, or an empty string) if the array is empty. However, this can lead to unexpected behavior when dealing with non-empty arrays that have falsy values.
* Using `for` loop: You can use a simple `for` loop to iterate over each element of the array and check if it's empty.

Keep in mind that these alternatives may have different performance characteristics than the original approaches being compared.

Related benchmarks:

Test if array is empty (version: 0)

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

Created: 4 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):