Benchmark: Check object. typeof vs constructor

Script Preparation code:

var obj = {a: 'val1'};

Tests:

typeof
typeof(obj) === 'object'
constructor
obj.constructor === Object

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
constructor

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

Browser/OS: Firefox 142 on Linux

View result in a separate tab

Test name	Executions per second
typeof	1513487488.0 Ops/sec
constructor	1560321408.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The MeasureThat.net benchmark measures the performance difference between two approaches to checking if an object is of type `object` in JavaScript:

1. Using the `typeof` operator (`typeof obj === 'object'`)
2. Using the `constructor` property of the object (`obj.constructor === Object`)

**Options Compared**

Two options are being compared:

1. **Using `typeof`**: This method uses the built-in `typeof` operator to check if an object is of type `object`.
2. **Using `constructor`**: This method checks if the constructor of an object is equal to the global `Object` constructor.

**Pros and Cons**

Here's a brief analysis of each approach:

* **Using `typeof`**:
	+ Pros: Simple, widely supported, and efficient.
	+ Cons: Can return incorrect results for certain types of objects (e.g., arrays) or when used with `null`.
* **Using `constructor`**:
	+ Pros: More accurate than `typeof`, as it checks the actual constructor function, not just its name.
	+ Cons: Requires accessing the object's properties and may be slower due to the additional lookup.

**Library Usage**

In this benchmark, no libraries are explicitly mentioned. However, the use of the global `Object` constructor implies that JavaScript is being executed in a context where this object is available and can be used as expected.

**Special JS Features/Syntax**

None of the special features or syntax (e.g., async/await, arrow functions, classes) are being utilized in this benchmark. The code is simple and straightforward.

**Other Alternatives**

If you're looking for alternative approaches to checking if an object is of type `object`, consider:

* **Using `instanceof`**: This method checks if an object is an instance of a specific constructor function (e.g., `Array` or `Object`). It's more precise than `typeof` but may not work with all types.
* **Using `isPrototypeOf()`**: This method checks if one object is in the prototype chain of another. It can be useful for certain use cases, such as checking if an object has a specific property.

Keep in mind that these alternatives might have different performance characteristics or trade-offs compared to the original approaches being tested in this benchmark.

Related benchmarks:

Check object. typeof vs constructor (version: 0)

Difference between typeof(a => {}) === 'object' and (a => {}).constructor === Object

Comparing performance of: typeof vs constructor

Created: 3 years ago by: Guest

Jump to the latest result

typeof

constructor

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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