Benchmark: var is a non-empty array (v3)

Script Preparation code:

var arr = [1,2,3];
var notArr = null;

Tests:

IsArray
const a = Array.isArray(arr) && arr.length > 0; const b = Array.isArray(notArr) && notArr.length > 0;
typecheck (nullable dot) (array)
const a = arr?.length > 0 && arr[0] !== undefined; const b = notArr?.length > 0 && notArr[0] !== undefined;
manual check cond
const a = arr !== null && arr !== undefined && arr.length > 0 && arr[0] !== undefined; const b = notArr !== null && notArr !== undefined && notArr.length > 0 && notArr[0] !== undefined;
typeof obj + length
const a = typeof arr === 'object' && arr !== null && arr.length > 0 && arr[0] !== undefined; const b = typeof notArr === 'object' && notArr !== null && notArr.length > 0 && notArr[0] !== undefined;
manual check with null-coalescing
const a = (arr ?? []).length > 0 && arr[0] !== undefined; const b = (notArr ?? []).length > 0 && notArr[0] !== undefined;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
IsArray
typecheck (nullable dot) (array)
manual check cond
typeof obj + length
manual check with null-coalescing

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/114.0

Browser/OS: Firefox 114 on Ubuntu

View result in a separate tab

Test name	Executions per second
IsArray	68048784.0 Ops/sec
typecheck (nullable dot) (array)	60658056.0 Ops/sec
manual check cond	54119092.0 Ops/sec
typeof obj + length	60121332.0 Ops/sec
manual check with null-coalescing	46595428.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared options, pros and cons, and other considerations.

**Benchmark Overview**

The benchmark tests different methods of checking if an array is non-empty in JavaScript. An array is considered non-empty if it has at least one element. The test cases cover various approaches to achieve this:

1. Using the `Array.isArray()` method
2. Using a nullable dot notation (`arr?.length > 0`)
3. Manual checks with multiple conditions (`arr !== null && arr !== undefined && arr.length > 0`)
4. Checking if an object has a `length` property and is not null (`typeof obj === 'object' && ...`)
5. Using the null-coalescing operator (`??`) to provide a default value for `arr` or `notArr`

**Test Cases**

The test cases are designed to measure the performance of each approach in different scenarios:

1. **IsArray**: Tests using the `Array.isArray()` method.
2. **typecheck (nullable dot) (array)**: Tests using the nullable dot notation (`arr?.length > 0`).
3. **manual check cond**: Manual checks with multiple conditions (`arr !== null && arr !== undefined && arr.length > 0`).
4. **typeof obj + length**: Checks if an object has a `length` property and is not null (`typeof obj === 'object' && ...`).
5. **manual check with null-coalescing**: Uses the null-coalescing operator (`??`) to provide a default value for `arr` or `notArr`.

**Comparison of Approaches**

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

1. **Array.isArray()**: This method is straightforward but can be slower due to the overhead of checking if an object is an array.
	* Pros: Easy to read and understand.
	* Cons: May be slower than other methods.
2. **Nullable Dot Notation**: This approach uses the optional chaining operator (`?.`) to access the `length` property, which returns `undefined` if the value is null or undefined.
	* Pros: Can be faster than explicit checks.
	* Cons: Requires support for the optional chaining operator in older browsers and Node.js versions.
3. **Manual Check**: This approach uses multiple conditions to check if an array is non-empty.
	* Pros: Highly customizable and can be more efficient than other methods.
	* Cons: Can be error-prone and harder to read due to the multiple conditions.
4. **typeof obj + length**: This approach checks if an object has a `length` property and returns its value.
	* Pros: Can be faster than explicit checks and provides additional information about the object.
	* Cons: Requires support for objects with a `length` property.
5. **Null-Coalescing Operator**: This operator provides a default value for `arr` or `notArr` if they are null or undefined.
	* Pros: Can simplify code and reduce errors.
	* Cons: May be slower than other methods due to the overhead of evaluating the expression.

**Library Used**

The benchmark uses the `Array.isArray()` method, which is a built-in JavaScript function. It does not rely on any external libraries.

**Special JS Feature or Syntax**

The benchmark uses the optional chaining operator (`?.`) and the null-coalescing operator (`??`), which are part of the ECMAScript 2020 standard. If you're using an older version of JavaScript, these features may not be available.

**Alternatives**

If you need to test alternative approaches, consider the following:

* Using a static type checker like TypeScript or Flow to analyze your code and suggest optimizations.
* Implementing a custom array length check function to compare with the `Array.isArray()` method.
* Testing other methods for checking if an object has a specific property or method.

Keep in mind that the choice of approach depends on your specific use case, performance requirements, and target browsers or environments.

Related benchmarks:

var is a non-empty array (v3) (version: 0)

Micro-benchmark various method of checking for non-empty array on arbitrary variable

Comparing performance of: IsArray vs typecheck (nullable dot) (array) vs manual check cond vs typeof obj + length vs manual check with null-coalescing

Created: one year ago by: Guest

Jump to the latest result

IsArray

typecheck (nullable dot) (array)

manual check cond

typeof obj + length

manual check with null-coalescing

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):