Benchmark: checks if object has any key - Object.keys vs for key in 2

Script Preparation code:

var obj = {}
new Array(1000).map((item, index) => {
    obj[index] = index
})

Tests:

Object.keys
!!Object.keys(obj).length
for key .. in
for(let key in obj){ return true; } return false

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.keys
for key .. in

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:139.0) Gecko/20100101 Firefox/139.0

Browser/OS: Firefox 139 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Object.keys	78585144.0 Ops/sec
for key .. in	39456268.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of MeasureThat.net and understand what's being tested in this specific benchmark.

**Benchmark Definition**

The provided JSON defines two microbenchmarks:

1. **"checks if object has any key - Object.keys vs for key in 2"`**
This benchmark compares two approaches to check if an object has any keys:
	* `Object.keys(obj).length`: Uses the `Object.keys()` method to get an array of the object's own enumerable property names, and then checks the length of that array.
	* `for (let key in obj) { return true; } return false;`: Uses a traditional `for...in` loop to iterate over the object's properties and returns `true` as soon as it encounters a property, or `false` if no properties are found.

**Options Compared**

The two approaches differ in their syntax, performance, and potential pitfalls:

* **Object.keys()**: This method is more concise and modern. It uses a V8-specific internal function to iterate over the object's properties. The trade-off is that it requires JavaScript engines to support this method (most do).
* **for...in loop**: This approach is more traditional and widely supported across older browsers and environments. However, it can be slower and less efficient than `Object.keys()`.

**Pros and Cons**

**Object.keys():**

Pros:

* Concise and readable syntax
* Faster execution due to V8-specific optimization

Cons:

* May not work in older browsers or environments that don't support this method (e.g., Internet Explorer 11)

**for...in loop:**

Pros:

* Widely supported across older browsers and environments
* Can be useful for learning and debugging purposes

Cons:

* Less efficient due to the need to explicitly check for property existence
* Potentially slower execution

**Other Considerations**

* Both approaches assume that the object has at least one property. If the object is empty, `Object.keys()` will return an empty array, while the `for...in` loop will not execute.
* In modern JavaScript engines, `Object.keys()` is generally faster and more efficient than the `for...in` loop.

**Library Usage**

There doesn't seem to be any external libraries used in this benchmark. The two approaches rely solely on built-in JavaScript features.

**Special JS Features or Syntax**

None mentioned in this specific benchmark. However, it's worth noting that MeasureThat.net may use special JavaScript features or syntax to optimize performance or ensure compatibility across different browsers and environments.

**Other Alternatives**

For similar benchmarks, you might see other approaches such as:

* Using `hasOwnProperty()` instead of `Object.keys()`
* Comparing with regular expressions
* Using a custom function to check for property existence

These alternatives would depend on the specific requirements and constraints of the benchmark.

Related benchmarks:

checks if object has any key - Object.keys vs for key in 2 (version: 0)

Comparing performance of: Object.keys vs for key .. in

Created: 3 years ago by: Registered User

Jump to the latest result

Object.keys

for key .. in

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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