Benchmark: Array Test 12345

Script Preparation code:

var arr = 'no';

Tests:

Array isArray
Array.isArray(arr)
Obj check
!!arr && arr.constructor === Array;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array isArray
Obj check

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.

Measuring JavaScript performance is an essential task, especially when comparing different approaches to achieve the same result.

The provided JSON represents a benchmark test for two specific scenarios: checking if a variable is an array using `Array.isArray()` and another approach using double negation (`!!arr && arr.constructor === Array;`).

**What are tested?**

In this case, we're testing two options for verifying whether a JavaScript variable is an array:

1. **`Array.isArray(arr)`**: This function checks if the input `arr` is an instance of the `Array` class or prototype.
2. **`!!arr && arr.constructor === Array;`**: This approach uses double negation (`!!`) to check if `arr` is truthy and then verifies its constructor equals the `Array` constructor.

**Options comparison**

Here's a brief overview of each option:

### Option 1: `Array.isArray(arr)`

* **Pros**:
	+ Short and concise syntax.
	+ Sufficiently efficient, as it checks if `arr` is an instance of `Array`.
	+ Well-supported across modern browsers and JavaScript engines.
* **Cons**:
	+ May not work correctly for custom array-like objects (e.g., `Set`, `Map`) or native array types like `BigIntArray`.

### Option 2: `!!arr && arr.constructor === Array;`

* **Pros**:
	+ Works correctly with custom array-like objects and native array types.
	+ Allows for a more explicit check, which can be beneficial in certain scenarios.
* **Cons**:
	+ More verbose syntax compared to `Array.isArray(arr)`.
	+ Double negation (`!!`) can lead to unexpected behavior if not used carefully.

**Library usage**

There's no external library used in these test cases. However, the `Array` constructor and its prototype are part of the JavaScript language itself.

**Special JS features or syntax**

This benchmark doesn't use any special JavaScript features or syntax beyond what's described above.

Now, let's move on to some alternative approaches that could be considered for similar scenarios:

1. **Using a custom function**: You could create a reusable function that takes an array-like object as input and returns a boolean indicating whether it's an array.
2. **Using a library like Lodash**: If you need more advanced array-related functionality, a library like Lodash might be suitable.
3. **Checking for `Array.prototype` presence**: Some older browsers or environments might not support the `Array.isArray()` function. In such cases, checking if `Array.prototype` is present and then verifying if the input variable has an `array` property could serve as an alternative.

For a more comprehensive comparison of different approaches, you can explore other benchmarks on MeasuringThat.net or create your own using a framework like Benchmark.js.

Related benchmarks:

Array Test 12345 (version: 0)

Comparing performance of: Array isArray vs Obj check

Created: 4 years ago by: Guest

Jump to the latest result

Array isArray

Obj check

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):