Benchmark: Tyepof vs Array.isArray

Script Preparation code:

var a = [];

Tests:

typeof
for(let i =0; i < 1000000; i++) { const b = typeof a === 'object'; }
Array.isArray
for(let i =0; i < 1000000; i++) { const b = Array.isArray(a); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
Array.isArray

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
typeof	3.0 Ops/sec
Array.isArray	1.2 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the test cases and explain what's being tested.

**Benchmark Definition**
The provided JSON represents a JavaScript benchmark definition. It defines two test cases:

1. `typeof`:
	* The script preparation code creates an empty array `a`.
	* The benchmark definition uses a `for` loop to iterate 1,000,000 times.
	* Inside the loop, it checks if `a` is an object using the `typeof` operator.
2. `Array.isArray`:
	* The script preparation code remains the same as above (`var a = [];`).
	* The benchmark definition uses another `for` loop to iterate 1,000,000 times.
	* Inside the loop, it checks if `a` is an array using the `Array.isArray` function.

**Options Compared**
The test cases compare two approaches:

1. **typeof**: This method uses the `typeof` operator to check if a value is an object. The `typeof` operator returns a string indicating the type of the value (`"object"` in this case).
2. **Array.isArray**: This method uses the built-in `Array.isArray` function to check if a value is an array.

**Pros and Cons**

* **typeof**:
	+ Pros: Simple, lightweight, and widely supported.
	+ Cons: May not work correctly for all objects (e.g., arrays are objects in JavaScript), and can be slower due to the overhead of string comparison.
* **Array.isArray**:
	+ Pros: Specifically designed for checking array types, which makes it more accurate than `typeof`.
	+ Cons: Requires a separate function call, which may incur additional overhead.

**Other Considerations**

* Both tests assume that the input array is empty (`a = [];`). In a real-world scenario, you might want to test with an existing array.
* The number of iterations (1,000,000) is quite high, which can help reveal performance differences between the two approaches.

**Library**
There is no external library used in this benchmark. However, if we consider modern JavaScript engines, some features might be related to libraries or frameworks, such as:

* In the `typeof` test, checking if `a` is an object uses a built-in operator (`typeof`). This is not typically considered a "library" but rather part of the JavaScript language itself.
* In the `Array.isArray` test, using the built-in `Array.isArray` function implies that the engine or runtime environment provides this function.

**Special JS Features**
There are no special JavaScript features mentioned in the provided benchmark. However, if we were to extend this benchmark to explore other areas, some possibilities might include:

* Checking for specific object properties (e.g., using `in` operator).
* Using modern ES6+ features like destructuring or class expressions.

**Alternatives**
Some alternative approaches could be explored in a similar benchmark:

1. **Using a custom implementation**: Instead of relying on built-in operators, you might create a custom function to check if an array is present.
2. **Comparing different iteration methods**: You could test the performance of using `for` loops versus `while` loops or even iterative functions (e.g., `let i = 0; while (i < 1000000) { ... }`).
3. **Testing with more complex data structures**: Using an array with nested objects or other complex types might help reveal differences in performance between the two approaches.

Keep in mind that these alternatives would require modifications to the benchmark definition and script preparation code, as well as potentially adding new test cases to cover these scenarios.

Related benchmarks:

Tyepof vs Array.isArray (version: 0)

Comparing performance of: typeof vs Array.isArray

Created: one year ago by: Guest

Jump to the latest result

typeof

Array.isArray

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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