Benchmark: "array length === 0" vs "!(0 in array)"

Script Preparation code:

var get_array = () => Math.random() > 0.5 ? [5, 10, 15, 20, 25, 30] : []

Tests:

array.length
var is_empty = get_array().length === 0
index check
var is_empty = !(0 in get_array())

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array.length
index check

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; CrOS x86_64 14541.0.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36

Browser/OS: Chrome 107 on Chrome OS 14541.0.0

View result in a separate tab

Test name	Executions per second
array.length	3403985.8 Ops/sec
index check	3438706.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark definition and its test cases to explain what's being tested, compared, and analyzed.

**Benchmark Definition:**

The benchmark is defined by two different approaches to check if an array is empty:

1. `var is_empty = get_array().length === 0`
2. `var is_empty = !(0 in get_array())`

These two approaches test the same condition, but use different syntax and semantics.

**Approach 1: Using Array Length**

This approach checks if the length of an array is equal to 0. The `length` property returns the number of elements in the array.

Pros:

* Simple and straightforward.
* Easy to read and understand.

Cons:

* Requires modern JavaScript versions (ECMAScript 5+) that support dynamic property access (`get_array().length === 0`).
* May not be supported by older browsers or environments.

**Approach 2: Using Index Check**

This approach checks if the array is empty by checking if `0` is present in the array using the `in` operator. An empty array will return `false` because there are no properties (including `0`) to check for presence.

Pros:

* Works in older browsers and environments that don't support dynamic property access.
* Can be used with older JavaScript versions.

Cons:

* Less readable and less intuitive than Approach 1.
* May have performance implications due to the overhead of checking for presence.

**Library Used:**

None of the provided code uses any external libraries. The `get_array` function is defined inline, which means it's a self-contained, standalone function that generates an array with a random length between 0 and 6.

**Special JS Feature or Syntax:**

There are no special JavaScript features or syntax used in this benchmark definition. Both approaches use standard JavaScript syntax.

**Other Alternatives:**

If you wanted to compare these two approaches in more detail, you could also consider:

* Using the `Array.prototype.length` property and checking if it's equal to 0.
* Using a library like Lodash (`_.isEmpty`) or Underscore (`_.isEmpty`) which provides a standardized way of checking for empty arrays.
* Using a different approach altogether, such as using a custom implementation that checks for the presence of a sentinel value (e.g., `null` or `-1`) in the array.

For a complete benchmarking scenario, you might also want to include additional test cases that cover other aspects of array manipulation, such as concatenation, indexing, and sorting.

Related benchmarks:

"array length === 0" vs "!(0 in array)" (version: 0)

this is really stupid but is surprisingly close i guess

Comparing performance of: array.length vs index check

Created: one year ago by: Registered User

Jump to the latest result

array.length

index check

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):