Benchmark: Check function. typeof vs constructor + null check II

Script Preparation code:

var fun = a => {};

Tests:

typeof
typeof(fun) === 'function'
constructor
fun.constructor === Function

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
constructor

Fastest: N/A

Slowest: N/A

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

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Let's break down the benchmark test.

**What is tested:**

The benchmark tests two approaches to determine if an expression or value is a function:

1. `typeof(a => {}) === 'function'`
2. `(a => {}).constructor === Function`

Here, `a` is a variable that holds a function expression `fun = a => {};`. The goal is to compare the results of using `typeof` with and without accessing the `constructor` property.

**Options compared:**

Two options are being tested:

1. **`typeof(a => {}) === 'function'`**: This approach uses the `typeof` operator to check if the value of `a` is a function.
2. **`(a => {}).constructor === Function`**: This approach accesses the `constructor` property of an object created by calling `a => {};`, and then checks if it's equal to the global `Function` constructor.

**Pros and cons:**

1. **`typeof(a => {}) === 'function'`**:
	* Pros: Simple, widely supported, and fast.
	* Cons: May not work as expected for certain function expressions or in older browsers that don't support ES6 functions.
2. **`(a => {}).constructor === Function`**:
	* Pros: More explicit and potentially more accurate, but may be slower due to the extra property access.
	* Cons: Less common and might require additional setup (e.g., using `Object.create(null)` instead of just `{}`).

**Other considerations:**

Both approaches are related to how JavaScript handles function expressions. The first approach uses `typeof` with a functional expression, while the second approach uses an object literal created by calling the function.

**Library and special JS feature/syntax:**

No external libraries or advanced JavaScript features are required for this benchmark. It's purely focused on testing the behavior of `typeof` and the `constructor` property in different contexts.

Now, let's talk about alternatives:

Other approaches to test if a value is a function include:

* Using the `instanceof` operator with the `Function` constructor (`a => {} instanceof Function`)
* Creating an instance of a function using `new Function()` or `Function()()`
* Using a library like Lodash, which provides a built-in `isFunction` utility function.

However, these alternatives might not be as straightforward or widely supported as the original `typeof` approach.

Related benchmarks:

Check function. typeof vs constructor + null check II (version: 0)

Difference between typeof(a => {}) === 'function' and (a => {}).constructor === Function

Comparing performance of: typeof vs constructor

Created: 5 years ago by: Guest

Jump to the latest result

typeof

constructor

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):