Benchmark: array check vs string check

Script Preparation code:

const a = [1];
const b = 'hello';

Tests:

isArray
const a = [1]; if (Array.isArray(a)) { return true; }
typeof String
const b = 'hello'; if (typeof b === 'string') { return true; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isArray
typeof String

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON data to explain what's being tested, compared, and their pros/cons.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches:

1. **Array check**: Checking if a variable is an array using `Array.isArray()`.
2. **String check**: Checking if a variable is a string using `typeof` with the string literal `'string'`.

**Pros and Cons of each approach:**

* **Array check (`Array.isArray()`):**
	+ Pros:
		- Can be used for more types, not just arrays (e.g., objects, Set, Map).
		- More explicit and type-safe.
	+ Cons:
		- May have performance overhead due to the function call.
* **String check (`typeof 'string'`):**
	+ Pros:
		- Typically faster than `Array.isArray()` since it's a simple literal comparison.
	+ Cons:
		- Limited to strings only, which might not be desirable for all use cases.

**Library and syntax:**

There is no specific library mentioned in the provided JSON data. However, note that `Array.isArray()` is a built-in JavaScript method that doesn't rely on any external libraries.

**Special JS feature or syntax:**

No special JavaScript features or syntax are being tested in this benchmark.

Now, let's examine the test cases:

1. **isArray**: This test case checks if an array is indeed an array using `Array.isArray()`. It's likely to be a basic check.
2. **typeof String**: This test case checks if a string literal `'hello'` is indeed a string using `typeof 'string'`. Again, it's a basic check.

**Other alternatives:**

For this specific use case (checking if an element is of type array or string), you could also consider other approaches:

1. **Using `instanceof`**: You can use the `instanceof` operator to check if an object is an instance of a constructor function, like `Array.prototype`. This approach is more explicit and type-safe but might be slower than using `typeof`.
2. **Using `Type` objects**: In some browsers, you can access built-in `Type` objects (e.g., `Type.Array`) that provide methods for checking the type of an object.

However, these alternatives are not being tested in this specific benchmark.

Related benchmarks:

array check vs string check (version: 0)

What's faster, checking if a variable is an array or a string?

Comparing performance of: isArray vs typeof String

Created: 3 years ago by: Guest

Jump to the latest result

isArray

typeof String

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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